Can you safely mix universal coolant with dex-cool?

or any type of coolant? If so what kind a problem may it cause..if any...I used Advance Auto Parts...universal formula coolant in a 2002 Buick Rendezvous 3.4l...where it had Dex-cool or pink coolant in it...however I did flush the system out before using the Advance Coolant...Is there any advantage of using the Dex-cool over the Universal Coolant??? Is there any one that knows for sure???