Safely combining cold cooked meat with fresh cooked meat?

[issynoko]

I have some plain cold turkey mince left over from burritos and have just made a ragu with a second pack of it. Ragu is bubbling in the oven, the left overs are in the fridge. Can I add the left over meat safely? Do I need to heat it up on its own first and then stir it in? Any knowledge useful - thanks!

I see no reason not to just add it to the hot sauce, that would be just as fast a way to heat it up and therefore avoid any problems.
Seen the time and guess its a bit late now!