Added logic to the generate method to check if a filename with the generated it exists, if yes a new id will be generated.
If the generation fails three times an exception will be thrown.

Ugh, i just saw that there is a suffix property that should be used instead of hardcoding the suffix into the path like in my patch file.
Because there is no way to delete or reupload previously uploaded fixes i wont reprovide the changed verison to avoid confusion.

Did you actually see it happen? This requires that PHP random generator would give the same number in same microsecond for two processes. Is it a real problem?

I did not saw it happen but it could happen. And prevention is better then a late reaction.

fixed, thanks