This might help.

http://en.wikipedia.org/wiki/Blue_straggler

http://www.solstation.com/x-objects/bluestrag.htm

I dont believe there is any direct observational evidence of what happens when stars collide, but the blue straggler theory seems to be gaining support as a possible result of stars getting together.

Statistically the chances of two stars hittng each other during a galactic encounter are exceptionally low, but as the old saying goes. Never say never. Our chances of obseving such an encounter with any detail would be infantesimal