At first I was unconvinced because the other envelope does it too:
but on closer examination and a bit of testing it seems you may be right. Selecting and deleting the only point I can see does the trick.
However, I would suggest that Reaper's behaviour is not ideal since neither making the lane as tall as possible, nor zooming out horizontally to the sample level reveals the existence of a second point, which leaves the user none the wiser. Nor I think should it be possible to create them on top of each other without giving some kind of alert.
In any case I'm certain that I did not create new points there (for which I only ever use shift+click) since I never create a point at time zero because there is always one there by default already. I always just right click -> Set point value for these. So how did the second points get there? To unknowingly create one point without knowing it can be regarded as a misfortune. To do it twice looks like a bug ... IMHO of course!