Steps to reproduce:
1. Create a new series via AdminUI. Name it “Testseries”
2. Try to create another series “Testseries” via AdminUI. It will give you an error that the series “Testseries” already exists.
3. Create a new series via AdminUI. Name it “Testseries ” (← The space at the end is important). It will create a second series „Testseries“ (without the space).