diff --git a/wp-admin/custom-header.php b/wp-admin/custom-header.php
index a06756a280..8b2973fc11 100644
--- a/wp-admin/custom-header.php
+++ b/wp-admin/custom-header.php
@@ -1164,7 +1164,8 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 			'post_title' => basename($cropped),
 			'post_mime_type' => $image_type,
 			'guid' => $url,
-			'context' => 'custom-header'
+			'context' => 'custom-header',
+			'post_parent' => $parent_attachment_id,
 		);
 
 		return $object;
@@ -1180,8 +1181,12 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 	 * @return int Attachment ID.
 	 */
 	final public function insert_attachment( $object, $cropped ) {
+		$parent_id = isset( $object['post_parent'] ) ? $object['post_parent'] : null;
+		unset( $object['post_parent'] );
+
 		$attachment_id = wp_insert_attachment( $object, $cropped );
 		$metadata = wp_generate_attachment_metadata( $attachment_id, $cropped );
+
 		/**
 		 * Filters the header image attachment metadata.
 		 *
@@ -1193,6 +1198,11 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 		 */
 		$metadata = apply_filters( 'wp_header_image_attachment_metadata', $metadata );
 		wp_update_attachment_metadata( $attachment_id, $metadata );
+
+		if ( $parent_id ) {
+			$meta = add_post_meta( $attachment_id, '_wp_attachment_parent', $parent_id, true );
+		}
+
 		return $attachment_id;
 	}
 
@@ -1241,7 +1251,13 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 
 		$object = $this->create_attachment_object( $cropped, $attachment_id );
 
-		unset( $object['ID'] );
+		$previous = $this->get_previous_crop( $object );
+
+		if ( $previous ) {
+			$object['ID'] = $previous;
+		} else {
+			unset( $object['ID'] );
+		}
 
 		$new_attachment_id = $this->insert_attachment( $object, $cropped );
 
@@ -1396,4 +1412,32 @@ wp_nonce_field( 'custom-header-options', '_wpnonce-custom-header-options' ); ?>
 
 		return $header_images;
 	}
+
+	/**
+	 * Get the ID of a previous crop from the same base image.
+	 *
+	 * @since 4.9.0
+	 *
+	 * @param  array $object A crop attachment object.
+	 * @return int|false An attachment ID if one exists. False if none.
+	 */
+	public function get_previous_crop( $object ) {
+		$header_images = $this->get_uploaded_header_images();
+
+		// Bail early if there are no header images.
+		if ( empty( $header_images ) ) {
+			return false;
+		}
+
+		$previous = false;
+
+		foreach ( $header_images as $image ) {
+			if ( $image['attachment_parent'] === $object['post_parent'] ) {
+				$previous = $image['attachment_id'];
+				break;
+			}
+		}
+
+		return $previous;
+	}
 }
diff --git a/wp-includes/js/customize-models.js b/wp-includes/js/customize-models.js
index 372cad6273..e2a5dfbcd3 100644
--- a/wp-includes/js/customize-models.js
+++ b/wp-includes/js/customize-models.js
@@ -164,6 +164,7 @@
 
 			this.on('control:setImage', this.setImage, this);
 			this.on('control:removeImage', this.removeImage, this);
+			this.on('add', this.maybeRemoveOldCrop, this);
 			this.on('add', this.maybeAddRandomChoice, this);
 
 			_.each(this.data, function(elt, index) {
@@ -187,6 +188,25 @@
 			}
 		},
 
+		maybeRemoveOldCrop: function( model ) {
+			var newID = model.get( 'header' ).attachment_id || false,
+			 	oldCrop;
+
+			// Bail early if we don't have a new attachment ID.
+			if ( ! newID ) {
+				return;
+			}
+
+			oldCrop = this.find( function( item ) {
+				return ( item.cid !== model.cid && item.get( 'header' ).attachment_id === newID );
+			} );
+
+			// If we found an old crop, remove it from the collection.
+			if ( oldCrop ) {
+				this.remove( oldCrop );
+			}
+		},
+
 		maybeAddRandomChoice: function() {
 			if (this.size() === 1) {
 				this.addRandomChoice();
diff --git a/wp-includes/js/customize-models.min.js b/wp-includes/js/customize-models.min.js
index 0e7def5114..3ba2c87979 100644
--- a/wp-includes/js/customize-models.min.js
+++ b/wp-includes/js/customize-models.min.js
@@ -1 +1 @@
-!function(a,b){var c=b.customize;c.HeaderTool={},c.HeaderTool.ImageModel=Backbone.Model.extend({defaults:function(){return{header:{attachment_id:0,url:"",timestamp:_.now(),thumbnail_url:""},choice:"",selected:!1,random:!1}},initialize:function(){this.on("hide",this.hide,this)},hide:function(){this.set("choice",""),c("header_image").set("remove-header"),c("header_image_data").set("remove-header")},destroy:function(){var a=this.get("header"),d=c.HeaderTool.currentHeader.get("header").attachment_id;d&&a.attachment_id===d&&c.HeaderTool.currentHeader.trigger("hide"),b.ajax.post("custom-header-remove",{nonce:_wpCustomizeHeader.nonces.remove,wp_customize:"on",theme:c.settings.theme.stylesheet,attachment_id:a.attachment_id}),this.trigger("destroy",this,this.collection)},save:function(){this.get("random")?(c("header_image").set(this.get("header").random),c("header_image_data").set(this.get("header").random)):this.get("header").defaultName?(c("header_image").set(this.get("header").url),c("header_image_data").set(this.get("header").defaultName)):(c("header_image").set(this.get("header").url),c("header_image_data").set(this.get("header"))),c.HeaderTool.combinedList.trigger("control:setImage",this)},importImage:function(){var a=this.get("header");void 0!==a.attachment_id&&b.ajax.post("custom-header-add",{nonce:_wpCustomizeHeader.nonces.add,wp_customize:"on",theme:c.settings.theme.stylesheet,attachment_id:a.attachment_id})},shouldBeCropped:function(){return(this.get("themeFlexWidth")!==!0||this.get("themeFlexHeight")!==!0)&&((this.get("themeFlexWidth")!==!0||this.get("themeHeight")!==this.get("imageHeight"))&&((this.get("themeFlexHeight")!==!0||this.get("themeWidth")!==this.get("imageWidth"))&&((this.get("themeWidth")!==this.get("imageWidth")||this.get("themeHeight")!==this.get("imageHeight"))&&!(this.get("imageWidth")<=this.get("themeWidth")))))}}),c.HeaderTool.ChoiceList=Backbone.Collection.extend({model:c.HeaderTool.ImageModel,comparator:function(a){return-a.get("header").timestamp},initialize:function(){var a=c.HeaderTool.currentHeader.get("choice").replace(/^https?:\/\//,""),b=this.isRandomChoice(c.get().header_image);this.type||(this.type="uploaded"),"undefined"==typeof this.data&&(this.data=_wpCustomizeHeader.uploads),b&&(a=c.get().header_image),this.on("control:setImage",this.setImage,this),this.on("control:removeImage",this.removeImage,this),this.on("add",this.maybeAddRandomChoice,this),_.each(this.data,function(b,c){b.attachment_id||(b.defaultName=c),"undefined"==typeof b.timestamp&&(b.timestamp=0),this.add({header:b,choice:b.url.split("/").pop(),selected:a===b.url.replace(/^https?:\/\//,"")},{silent:!0})},this),this.size()>0&&this.addRandomChoice(a)},maybeAddRandomChoice:function(){1===this.size()&&this.addRandomChoice()},addRandomChoice:function(a){var b=RegExp(this.type).test(a),c="random-"+this.type+"-image";this.add({header:{timestamp:0,random:c,width:245,height:41},choice:c,random:!0,selected:b})},isRandomChoice:function(a){return/^random-(uploaded|default)-image$/.test(a)},shouldHideTitle:function(){return this.size()<2},setImage:function(a){this.each(function(a){a.set("selected",!1)}),a&&a.set("selected",!0)},removeImage:function(){this.each(function(a){a.set("selected",!1)})}}),c.HeaderTool.DefaultsList=c.HeaderTool.ChoiceList.extend({initialize:function(){this.type="default",this.data=_wpCustomizeHeader.defaults,c.HeaderTool.ChoiceList.prototype.initialize.apply(this)}})}(jQuery,window.wp);
\ No newline at end of file
+!function(a,b){var c=b.customize;c.HeaderTool={},c.HeaderTool.ImageModel=Backbone.Model.extend({defaults:function(){return{header:{attachment_id:0,url:"",timestamp:_.now(),thumbnail_url:""},choice:"",selected:!1,random:!1}},initialize:function(){this.on("hide",this.hide,this)},hide:function(){this.set("choice",""),c("header_image").set("remove-header"),c("header_image_data").set("remove-header")},destroy:function(){var a=this.get("header"),d=c.HeaderTool.currentHeader.get("header").attachment_id;d&&a.attachment_id===d&&c.HeaderTool.currentHeader.trigger("hide"),b.ajax.post("custom-header-remove",{nonce:_wpCustomizeHeader.nonces.remove,wp_customize:"on",theme:c.settings.theme.stylesheet,attachment_id:a.attachment_id}),this.trigger("destroy",this,this.collection)},save:function(){this.get("random")?(c("header_image").set(this.get("header").random),c("header_image_data").set(this.get("header").random)):this.get("header").defaultName?(c("header_image").set(this.get("header").url),c("header_image_data").set(this.get("header").defaultName)):(c("header_image").set(this.get("header").url),c("header_image_data").set(this.get("header"))),c.HeaderTool.combinedList.trigger("control:setImage",this)},importImage:function(){var a=this.get("header");void 0!==a.attachment_id&&b.ajax.post("custom-header-add",{nonce:_wpCustomizeHeader.nonces.add,wp_customize:"on",theme:c.settings.theme.stylesheet,attachment_id:a.attachment_id})},shouldBeCropped:function(){return(this.get("themeFlexWidth")!==!0||this.get("themeFlexHeight")!==!0)&&((this.get("themeFlexWidth")!==!0||this.get("themeHeight")!==this.get("imageHeight"))&&((this.get("themeFlexHeight")!==!0||this.get("themeWidth")!==this.get("imageWidth"))&&((this.get("themeWidth")!==this.get("imageWidth")||this.get("themeHeight")!==this.get("imageHeight"))&&!(this.get("imageWidth")<=this.get("themeWidth")))))}}),c.HeaderTool.ChoiceList=Backbone.Collection.extend({model:c.HeaderTool.ImageModel,comparator:function(a){return-a.get("header").timestamp},initialize:function(){var a=c.HeaderTool.currentHeader.get("choice").replace(/^https?:\/\//,""),b=this.isRandomChoice(c.get().header_image);this.type||(this.type="uploaded"),"undefined"==typeof this.data&&(this.data=_wpCustomizeHeader.uploads),b&&(a=c.get().header_image),this.on("control:setImage",this.setImage,this),this.on("control:removeImage",this.removeImage,this),this.on("add",this.maybeRemoveOldCrop,this),this.on("add",this.maybeAddRandomChoice,this),_.each(this.data,function(b,c){b.attachment_id||(b.defaultName=c),"undefined"==typeof b.timestamp&&(b.timestamp=0),this.add({header:b,choice:b.url.split("/").pop(),selected:a===b.url.replace(/^https?:\/\//,"")},{silent:!0})},this),this.size()>0&&this.addRandomChoice(a)},maybeRemoveOldCrop:function(a){var b,c=a.get("header").attachment_id||!1;c&&(b=this.find(function(b){return b.cid!==a.cid&&b.get("header").attachment_id===c}),b&&this.remove(b))},maybeAddRandomChoice:function(){1===this.size()&&this.addRandomChoice()},addRandomChoice:function(a){var b=RegExp(this.type).test(a),c="random-"+this.type+"-image";this.add({header:{timestamp:0,random:c,width:245,height:41},choice:c,random:!0,selected:b})},isRandomChoice:function(a){return/^random-(uploaded|default)-image$/.test(a)},shouldHideTitle:function(){return this.size()<2},setImage:function(a){this.each(function(a){a.set("selected",!1)}),a&&a.set("selected",!0)},removeImage:function(){this.each(function(a){a.set("selected",!1)})}}),c.HeaderTool.DefaultsList=c.HeaderTool.ChoiceList.extend({initialize:function(){this.type="default",this.data=_wpCustomizeHeader.defaults,c.HeaderTool.ChoiceList.prototype.initialize.apply(this)}})}(jQuery,window.wp);
\ No newline at end of file
diff --git a/wp-includes/theme.php b/wp-includes/theme.php
index 6909d0fe2e..2ee66fbddf 100644
--- a/wp-includes/theme.php
+++ b/wp-includes/theme.php
@@ -1214,6 +1214,7 @@ function get_uploaded_header_images() {
 		$header_images[$header_index]['url'] =  $url;
 		$header_images[$header_index]['thumbnail_url'] = $url;
 		$header_images[$header_index]['alt_text'] = get_post_meta( $header->ID, '_wp_attachment_image_alt', true );
+		$header_images[$header_index]['attachment_parent'] = (int) get_post_meta( $header->ID, '_wp_attachment_parent', true );
 
 		if ( isset( $header_data['width'] ) )
 			$header_images[$header_index]['width'] = $header_data['width'];
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 0f6a55c375..15b58e59c6 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -4,7 +4,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '4.9-alpha-41731';
+$wp_version = '4.9-alpha-41732';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.