A Better Finder Rename automatically resolves file name conflicts by adding one or more “distinguisher” characters at the end of the conflicting file names.
Let’s say you remove the last digit from the following file names:
Image1112.gif
Image1113.gif
The new file names would become:
Image111.gif
Image111.gif
which isn’t possible because within each folder only one file can have a particular name.
In this case, A Better Finder Rename resolves the conflict by adding a distinguisher to the end of the file names:
Image111 (a).gif
Image111 (b).gif
You can configure exactly how file name conflicts are resolved.