Windows: how to change file autonumbering template?

F.ex. I rename file 'Picture1.jpg' to 'symph-40.jpg' in Explorer. It says that 'There is already a file with the same name in this location.' and suggests to rename into 'symph-40 (2).jpg'. I want it would suggested me 'symph-40.2.jpg' instead. Where it keeps auto-renaming template for such cases?