I did something similar, a while back for my orks (it was 1:1 orkhide shade/goblin green, don't know the new names)
I just dumped 1 pot of each into a plastic cup, stirred like a madman, then carefully poured it back into the two pots (then peeled off the labels). Worked fine for me
Given how watery most
GW acrylics are, you won't waste too much that way.