Errors during the upload - Can't re-upload?

I had 4 files fail during the upload. I got the error message that they failed due to internet issues ..... so ..... I resubmitted them.
Now I get the following message ..... You have already uploaded this file. Please see our upload guidelines.

What is the best way to resubmit to get the software to not block me?

Change the filenames then upload again, and it'll let them through.