[f8]Suddenly a duplicated frame

I'm working on - or trying to - a template. I was changing some text in a frame, and now find that the frame suddenly has a twin with little icons of empty oblongs instead of the spheres the others have.

One is Frame 3 and the other Frame 4, yet there is no obvious division as there is between the other frames.

I think I should delete it, but can't find how to.

An option is to make it the new last frame which could be quite useful - if only I knew how to move it along.

Be grateful for guidance, please.

Found the way to remove a frame, but not to copy and paste in a frame ...