Duplicate screenshot file name blocks submitting a blueprint

[luziferius]

I got this error message

Error submitting blueprint

    File with name reactor.png already exists.

upon clicking the Save button, and blueprint submission is denied. But there is no way to delete or rename the attached screenshot.
Thus the submission is blocked indefinitely and has to be restarted from scratch.

(Edit:) After a re-try without any screenshot attached, the page told me that it requires exactly one screenshot. Trying to drop another over an already selected screenshot does replace it.

Reproduction

• Create a BP submission
• Attach a screenshot with a name already in the database
• Try to click Save
• No way to resolve the error, except by completely starting over (Edit: Dropping a new file does replace the old one, but this is not communicated.)

Suggested solutions

Any one of these is fine:

• (Edit:) Notify the user that selecting a screenshot with a different name will solve this. Add "Add a screenshot with different name to replace the offending file" to the error message, to make the solution process clear.
• Automatically rename submitted screenshots. Maybe anonymize the file names and rename all submitted files using a UUID-based naming scheme.
• Allow renaming attached screenshots during the submission
• Allow removing attached screenshots during the submission
• Only enforce unique names across a single account?