In pro Tools you can paste anywhere, on a blank piece of track or in an existing piece of track, it makes no difference and from memory Cubase is the same. But, Studio One does not allow you to paste on top of an existing track as you would if you were dropping in a snare drum let's say for a duff one, UNLESS... you use the keyboard control & V.
I would suggest that's an error and needs to be rectified, there's absolutely no reason for it not to paste on an existing piece of track from your right-click. It's called workflow. 