Sitecore Media Upload Dialog - Duplicate Item Name Validation Error

In Sitecore Media Library, multiple items with same name is denied by default. This is configured by the setting AllowDuplicateItemNamesOnSameLevel. Default it is set to false to restrict the duplication.

If a content author uploads a media item in a folder which has an item with same name, then Upload File dialog will throw an error. "An error occured while uploading a file. The reason may be that the file does not exist or the path is wrong.". This is not a meaningful error to the content authors. 

1984 14:44:04 ERROR Could not save posted file: Related Items.png
Exception: Sitecore.Exceptions.DuplicateItemNameException
Message: The item name "Related Items" is already defined on this level.
Source: Sitecore.Kernel
   at Sitecore.Data.Items.ItemUtil.AssertDuplicateItemName(Item destinationItem, Item sourceItem, String name)
   at Sitecore.Data.Items.ItemUtil.AssertItemName(Item destinationItem, Item sourceItem, String name)
   at Sitecore.Data.Items.Item.Add(String name, TemplateID templateID)
   at Sitecore.Resources.Media.MediaCreator.CreateItem(String itemPath, String filePath, MediaCreatorOptions options)
   at Sitecore.Resources.Media.MediaCreator.AttachStreamToMediaItem(Stream stream, String itemPath, String fileName, MediaCreatorOptions options)
   at Sitecore.Resources.Media.MediaCreator.CreateFromStream(Stream stream, String filePath, MediaCreatorOptions options)
   at Sitecore.Resources.Media.MediaUploader.UploadToDatabase(List`1 list)
   at Sitecore.Resources.Media.MediaUploader.Upload()
   at Sitecore.Pipelines.Upload.Save.Process(UploadArgs args)

In order to provide content author with meaningful error message, you can overwrite the Upload Media dialog and render a meaning error message. sitecore.shell.Applications.Media.UploadMedia.UploadMediaPage2 Dialog has to be modified. Sample code is placed in this repo.