but 2010 ram should work. so if you have a pair of 4gb sticks of 1066 pc3-8500 ram from the 2010 and stick it in the 2012 mini it will run. it is complicated if it is worth doing .
1 ) it is free
2) if you are going from 2 x 2gb in the 2012 to 2x 4gb from the 2010 you have more ram
3) the 2010 is slower
4) if I have a 4 seat very fast car and 6 passengers I need multiple trios therefor a slower 8 seat mini van is better.
5) so if you put the 2010 ram in the new mini and use 2-4gb ram you will lose in speed but if you use 4 to 8gb in ram you will win out.
6) since it is free and should not break your machine try it with the stock 1600 ram and the 1066 ram from the 2010.