No it doesn't have to show both ways. When you say "just" got it, you mean like yesterday or something? If you've only put a few miles/few days on it, take it back if it's a dealer and if a private party ask them for compensation. If they claimed a rebuild and you had a bad head gasket in the next 100 miles, they have misrepresented the car to you and you should go to Small Claims court.
If you've had the car a few months, then you're probably SOL here.
As for fixing it, this depends on what you paid and what kind of shape it is in. If it's a shabby '94 and you're only in it maybe $1500 bucks, I'd bail on it unless you are a do-it-yourselfer.
But by all means, verify the bad head gasket by testing.