That appears less like a collision (Things hitting things) than a merger(Things combining).
Just like electrons in atoms, galaxies have SO MUCH empty space in them that even with they occupy the same location, there are very few actual smashing collisions of stars. Or so I've read. I haven't been able to witness too many galaxies passing through each other in my lifetime, sad to say!!
When galaxies merge, a lot of stars are tossed off into intergalactic space, in order to preserve momentum and energy. Sort of like an inelastic collision, but instead of turning kinetic energy into heat, it's bled off by "boiling off" some stars gravitationally. Sort of a large scale collision.