Since we now get to pick a back-up colour encase our 1st choice colour is taken and there's an achievement for denying a player their colour, do we get an achievement if we deny someone their 2nd choice colour?

I think there should be...

Say its a 3v3 game.
Player A gets green and green is your color (you are player B). Player C is also green. So player B receives his secondary color Blue and thus denies Player C of his secondary color blue.....

Assuming that the lvls of players go as A>B>C