#399

backend/app/services/post_import_previewer.rb

@@ -164,7 +164,10 @@ class PostImportPreviewer
                     video_ms: parse_duration(attributes['duration'], errors))
     post.valid?
     post.errors.each { |error| (errors[error.attribute] ||= []) << error.message }
-    errors.delete(:url)
+    if errors[:url]
+      errors[:url].reject! { |message| message.include?('すでに存在') || message.include?('taken') }
+      errors.delete(:url) if errors[:url].empty?
+    end
   end
 
   def parse_duration value, errors