Nah it's because after SainTD's brother who won 2nd place in Toribash $1000 tourney could make a custom color for himself and he chose demon, but now named I dunno how he named, but it's basically same demon color
so now to get achievement you need to get his custom demon color as well (e.g. it's gliched)
For more info, google toribash $1000 tourney
source - wikipedia commons