If Person 2 always lies, and they said that Person 1 always tells the truth, then we would have to assume that person one actually always lies, so their statement that Person 2 always lies would have to be a lie, so they would actually tell the truth... But then, that would mean that Person 2's statement that Person 1 always tells the truth would have to be true, and that would mean that Person 2 tells lies...
I don't think it's possible to come up with an answer with this... It's a perpetual loop of questioning both of their statements, and no way to find out who is actually telling the truth.