Basic copy and paste?

paste that section in a different track instead. I think what you did is you made a new take, which plays INSTEAD OF the other selection, not on top of it.

Sounds like you've got track lanes on.

Hi. If you are doing this to hide the clicking noise, why not try Spectro? (You can get a lower cost Reaper vst version). It might be able to allow you to isolate the click noise and then delete or fade it. I think it's amazing. Get it from here: Cheers.