Hi,

is it possible to have an output video that contains 2 clips at the same time, one on top of the other for example (or any other arrangement)?

Thank you

Yes, you can make this picture in picture (PiP) effect. The question has been answered several times here, hence the short HOWTO version: Add two clips to two tracks, let them overlap, add a Composite transition between them, apply effects to change the size and place of one or both clips. Play around and see.