Any two alcohol molecules can react producing ether.
If you have just one alcohol, every time two molecules react they are identical, so what is produced is a diX ether - be it diethyl or dimethyl (two white marbles when all marbles are white, or two black marbles when all marbles are black).
But if you have a mixture of both alcohols, two molecules that react can be either identical (two whites or two blacks) or two different (white and black), so there are three possible products.