Thanks for taking the time to report this!
To resolve issues, it helps to have exact steps to reproduce.
Could you provide a list of steps to reproduce the problem (and translate to English for the developers)? What does "redundant title" mean? Is this about duplicated file names like in T42109?

Thanks in advance!

Could you provide a list of steps to reproduce the problem

I don't think steinsplitter is reporting a problem he has experienced, but one that was reported by another user at commons (and its probably an intermittent problem at that). The original reporter is probably not seeing this report.

Translations to english appreciated...

From Google Translate:

In case of failure suppression by a redundant title can no longer press on Upload again, so you have to repeat the work for nothing.

This sounds like T48741 or T106968, both of which I fixed last week. @Steinsplitter, if you speak German, can you contact the bug reporter and ask if this is still a problem?

BTW: I experienced the same problem on 14.09.15!
I tried to upload ~30 files, which had the same name but with a different file extension, which the upload wizard didn't accept.
After giving them a unique name I also forgot to enter a valid date for each file.
After trying to reload my files the "continue" button (or similar text) was not there.
Maybe it has to do with the missing date?
(Maybe if I first gave each file a date and after that entered a unique file name I do not remember.)
Greetings