Hello,

I saw the screenshot you attached.

The overlap column works for the row that is inside the row. This means that you need to have the row inside the other row then the content will overlap.

Screenshot for Clarification: https://ibb.co/yyGpHY8

You can also check the following link for help:
https://kb.wpbakery.com/docs/wpbakery-page-builder-how-tos/how-to-insert-inner-row/

Regards.
Xtemos Studios.