SUMMARY When mass renaming with dolphin, if a folder's name ends with a stop then one or two characters, which are both the same, then these characters are preserved in the final folder's name. STEPS TO REPRODUCE 1. Create two folders, test.aa and test2.ab, in an empty folder 2. Select both and right-click -> rename 3. Enter # into the rename pattern box, and 1 as the initial number. OBSERVED RESULT Two folders are created: 1.aa and 2 EXPECTED RESULT The folders should be named 1 and 2 SOFTWARE/OS VERSIONS Fedora 30 KDE Plasma Version: 5.15.4 KDE Frameworks Version: 5.55.0 Qt Version: 5.12.1 ADDITIONAL INFORMATION
Dolphin checks for known extensions. A folder named "test.jpeg" will keep its extension on rename, like it is kept for renaming files. I am not sure if there are registered folder name extensions, such as for mailbox directories etc. If there are, they really should be preserved. Maybe the MIME database knows extensions that apply to folder names.
Okay, I can see that this is intentional.