diff --git a/lib/import_export/category_importer.rb b/lib/import_export/category_importer.rb
index 8493b006a09..b432bd078bf 100644
--- a/lib/import_export/category_importer.rb
+++ b/lib/import_export/category_importer.rb
@@ -39,14 +39,15 @@ module ImportExport
 
     def import_categories
       id = @export_data[:category].delete(:id)
+      import_id = "#{id}#{import_source}"
 
-      parent = CategoryCustomField.where(name: 'import_id', value: id.to_s).first.try(:category)
+      parent = CategoryCustomField.where(name: 'import_id', value: import_id).first.try(:category)
 
       unless parent
         permissions = @export_data[:category].delete(:permissions_params)
         parent = Category.new(@export_data[:category])
         parent.user_id = @topic_importer.new_user_id(@export_data[:category][:user_id]) # imported user's new id
-        parent.custom_fields["import_id"] = id
+        parent.custom_fields["import_id"] = import_id
         parent.permissions = permissions.present? ? permissions : { "everyone" => CategoryGroup.permission_types[:full] }
         parent.save!
         set_category_description(parent, @export_data[:category][:description])
@@ -54,14 +55,15 @@ module ImportExport
 
       @export_data[:subcategories].each do |cat_attrs|
         id = cat_attrs.delete(:id)
-        existing = CategoryCustomField.where(name: 'import_id', value: id.to_s).first.try(:category)
+        import_id = "#{id}#{import_source}"
+        existing = CategoryCustomField.where(name: 'import_id', value: import_id).first.try(:category)
 
         unless existing
           permissions = cat_attrs.delete(:permissions_params)
           subcategory = Category.new(cat_attrs)
           subcategory.parent_category_id = parent.id
           subcategory.user_id = @topic_importer.new_user_id(cat_attrs[:user_id])
-          subcategory.custom_fields["import_id"] = id
+          subcategory.custom_fields["import_id"] = import_id
           subcategory.permissions = permissions.present? ? permissions : { "everyone" => CategoryGroup.permission_types[:full] }
           subcategory.save!
           set_category_description(subcategory, cat_attrs[:description])
@@ -79,5 +81,9 @@ module ImportExport
     def import_topics
       @topic_importer.import_topics
     end
+
+    def import_source
+      @_import_source ||= "#{ENV['IMPORT_SOURCE'] || ''}"
+    end
   end
 end
diff --git a/lib/import_export/topic_importer.rb b/lib/import_export/topic_importer.rb
index 6b1d9f5d268..721536d7227 100644
--- a/lib/import_export/topic_importer.rb
+++ b/lib/import_export/topic_importer.rb
@@ -18,14 +18,15 @@ module ImportExport
 
     def import_users
       @export_data[:users].each do |u|
+        import_id = "#{u[:id]}#{import_source}"
         existing = User.with_email(u[:email]).first
         if existing
-          if existing.custom_fields["import_id"] != u[:id]
-            existing.custom_fields["import_id"] = u[:id]
+          if existing.custom_fields["import_id"] != import_id
+            existing.custom_fields["import_id"] = import_id
             existing.save!
           end
         else
-          u = create_user(u, u[:id]) # see ImportScripts::Base
+          u = create_user(u, import_id) # see ImportScripts::Base
         end
       end
       self
@@ -37,13 +38,15 @@ module ImportExport
         print t[:title]
 
         first_post_attrs = t[:posts].first.merge(t.slice(*(TopicExporter::TOPIC_ATTRS - [:id, :category_id])))
+
         first_post_attrs[:user_id] = new_user_id(first_post_attrs[:user_id])
         first_post_attrs[:category] = new_category_id(t[:category_id])
 
-        first_post = PostCustomField.where(name: "import_id", value: first_post_attrs[:id]).first.try(:post)
+        import_id = "#{first_post_attrs[:id]}#{import_source}"
+        first_post = PostCustomField.where(name: "import_id", value: import_id).first&.post
 
         unless first_post
-          first_post = create_post(first_post_attrs, first_post_attrs[:id])
+          first_post = create_post(first_post_attrs, import_id)
         end
 
         topic_id = first_post.topic_id
@@ -51,10 +54,17 @@ module ImportExport
         t[:posts].each_with_index do |post_data, i|
           next if i == 0
           print "."
-          existing = PostCustomField.where(name: "import_id", value: post_data[:id]).first.try(:post)
+          post_import_id = "#{post_data[:id]}#{import_source}"
+          existing = PostCustomField.where(name: "import_id", value: post_import_id).first&.post
           unless existing
-            create_post(post_data.merge(topic_id: topic_id,
-                                        user_id: new_user_id(post_data[:user_id])), post_data[:id]) # see ImportScripts::Base
+            # see ImportScripts::Base
+            create_post(
+              post_data.merge(
+                topic_id: topic_id,
+                user_id: new_user_id(post_data[:user_id])
+              ),
+              post_import_id
+            )
           end
         end
       end
@@ -65,12 +75,16 @@ module ImportExport
     end
 
     def new_user_id(external_user_id)
-      ucf = UserCustomField.where(name: "import_id", value: external_user_id.to_s).first
+      ucf = UserCustomField.where(name: "import_id", value: "#{external_user_id}#{import_source}").first
       ucf ? ucf.user_id : Discourse::SYSTEM_USER_ID
     end
 
     def new_category_id(external_category_id)
-      CategoryCustomField.where(name: "import_id", value: external_category_id).first.category_id rescue nil
+      CategoryCustomField.where(name: "import_id", value: "#{external_category_id}#{import_source}").first.category_id rescue nil
+    end
+
+    def import_source
+      @_import_source ||= "#{ENV['IMPORT_SOURCE'] || ''}"
     end
   end
 end