elements appear again after they were deleted

Sometimes I do a copy/paste of elements just to position things on another form…

Not so often, not reproducable either, but sometimes when I deleted the elements they reappear again after I navigated to another form an navigated back.

Up untill today I thought this was my mistake but just the other minute it happened to me with 6 different forms where I was sure that I navigated out of them with a ‘nice and clean’ look…

is this only happening when elements that you have copied from another form?

I think so, but I am not sure about that. At least this was the case today…