Changing the processed file name

I've somehow got sticky names. As I scroll through a collection and select ones to process, every one will share the same image title. So rather than end up with a develops folder with Image a.tif b.tif c.tif, I'm creating a.tif a1.tif a2.tif.

What did I do (so I can not do it again)

How do I stop it (so I don't have to delete the Image title for each, letting C1 use the file name instead)