I must say its my best till yet. I created two galaxies. One with mass of one Milkey way, the other with 0,89 Milkey Way.
I deleted the galaxies and placed a black hole in each center. Then i clicked "orbit all".
The two galaxies fused and the central black holes came closer each other.
At end both black holes merged too one and then the interesting stuff happend. The most inner stars did speed up and formed a ring that drifted outwards and the other stars close too the supermassive black hole in center are kind of "pulsing".
Just look the video i made, i love it:
http://www.youtube.com/watch?v=48LVf--i4rYThe most fascinating aspect is, that there are galaxies that had that kind of collission who look exactly the same: