diff --git a/wp-includes/l10n/class-wp-translation-file-mo.php b/wp-includes/l10n/class-wp-translation-file-mo.php
index 225b48a836..bf39cc70ec 100644
--- a/wp-includes/l10n/class-wp-translation-file-mo.php
+++ b/wp-includes/l10n/class-wp-translation-file-mo.php
@@ -161,7 +161,15 @@ class WP_Translation_File_MO extends WP_Translation_File {
 					$this->headers[ strtolower( $name ) ] = $value;
 				}
 			} else {
-				$this->entries[ (string) $original ] = $translation;
+				/*
+				 * In MO files, the key normally contains both singular and plural versions.
+				 * However, this just adds the singular string for lookup,
+				 * which caters for cases where both __( 'Product' ) and _n( 'Product', 'Products' )
+				 * are used and the translation is expected to be the same for both.
+				 */
+				$parts = explode( "\0", (string) $original );
+
+				$this->entries[ $parts[0] ] = $translation;
 			}
 		}
 
diff --git a/wp-includes/l10n/class-wp-translation-file-php.php b/wp-includes/l10n/class-wp-translation-file-php.php
index 9f5b5abd98..f93dd0163f 100644
--- a/wp-includes/l10n/class-wp-translation-file-php.php
+++ b/wp-includes/l10n/class-wp-translation-file-php.php
@@ -28,12 +28,8 @@ class WP_Translation_File_PHP extends WP_Translation_File {
 		}
 
 		if ( isset( $result['messages'] ) && is_array( $result['messages'] ) ) {
-			foreach ( $result['messages'] as $singular => $translations ) {
-				if ( is_array( $translations ) ) {
-					$this->entries[ $singular ] = implode( "\0", $translations );
-				} elseif ( is_string( $translations ) ) {
-					$this->entries[ $singular ] = $translations;
-				}
+			foreach ( $result['messages'] as $original => $translation ) {
+				$this->entries[ (string) $original ] = $translation;
 			}
 			unset( $result['messages'] );
 		}
diff --git a/wp-includes/l10n/class-wp-translations.php b/wp-includes/l10n/class-wp-translations.php
index 5992c855b6..e177e1d8c5 100644
--- a/wp-includes/l10n/class-wp-translations.php
+++ b/wp-includes/l10n/class-wp-translations.php
@@ -95,15 +95,10 @@ class WP_Translations {
 			$entry->context = $parts[0];
 		}
 
-		// Look for plural original.
-		$parts           = explode( "\0", $original );
-		$entry->singular = $parts[0];
-		if ( isset( $parts[1] ) ) {
-			$entry->is_plural = true;
-			$entry->plural    = $parts[1];
-		}
-
+		$entry->singular     = $original;
 		$entry->translations = explode( "\0", $translations );
+		$entry->is_plural    = count( $entry->translations ) > 1;
+
 		return $entry;
 	}
 
diff --git a/wp-includes/version.php b/wp-includes/version.php
index 1eb408e027..2753e3bee4 100644
--- a/wp-includes/version.php
+++ b/wp-includes/version.php
@@ -16,7 +16,7 @@
  *
  * @global string $wp_version
  */
-$wp_version = '6.5-alpha-57512';
+$wp_version = '6.5-alpha-57513';
 
 /**
  * Holds the WordPress DB revision, increments when changes are made to the WordPress DB schema.