If you upload the same video twice, the second upload will be a duplicate. The duplicate will have a status of "Upload failed: Duplicate upload" or “File is a duplicate of a video you have already uploaded” on the Videos page.
If you’d like to upload the same video again, try editing the video before uploading it. For example, change the video length by adding extra frames or compress the video. Changing the filename alone won’t prevent the duplicate upload error message.