Whenever I try to paste a picture onto the frame and then merge it, it's fine, until I try to do the same thing to the next frame.

Then the previous frame has the corner of a picture in the bottom right hand corner
and when I crtl+t it, it appears to be the frame I just merged, but I can't get rid of it.

No matter what I do all my frames/layers have the corner of the next frame on it.

I don't know if it's my photoshop or if I'm doing something wrong but I'd really appreciate some help because it's frustrating.

I have Photoshop 5 Extended