A breeder too much. How to remove?

Hello, I partly underlined 2 "_" between words in the file name. But sometimes only 1 "_".
Now I would like to remove one in the section where 2 underlines.
Example: test file__ for_personal computer
How do I do that? When I use the method, the second underlines will be removed, but also the sections where only one is underlined.
Reply to #1:
Replace method:

Replace: __
Replace with: _

Good luck!
Reply to #2:
Sometimes it's so easy. Thanks