1994 Ford Aerostar Blown head gasket on a 3.1 V6

I woiuld like to know if it is better to just replace the engine than to spend the time fixing a blown head gasket on one side of a v6 or would it be better to replace both head gaskets because I've been told that if you only fix the one side that later on the other side will blow and you will be back to the same problem that you just fixed!! Thanks.....