Weird result after copying selected metadata. Bug?

Weird result after copying selected metadata. Bug?

I just copied selected metadata from one photo to some others. Mainly email, adress, a.s.o… Quite by accident, I then saw, that the control points in the other photos, had been replaced by the control line from the photo, where I copied the metadata. But when comparing those with the exported jpegs, I could see, that the edits from the control points, still are there. But not shown under local adjustments. In the history, this control line is also visible.
First I thought, it was my fault, because I did not understand what is all included in the metadata. But the only thing, which was changed, besides, email, etc., was this control point.
I then tried to reproduce this. But no success. When copying the metadata from a photo with control line to a photo with control point, the control point stayed alive. Which I think, also should be the normal behaviour.
So now I am really at a loss and have no idea how this could happen. Any ideas? Maybe a bug after all?