A two piece mast is definitely not right. Could be that you have a comptip mast (4' plastic top part with aluminum bottom part) that has been taken apart for some reason or you have a damaged, all aluminum mast that someone tried to sleeve (unsuccessfully?).
H16 from the late '80s on will have a factory comptip mast. Earlier boats will have an all aluminum mast or a mast that was modified with a comptip kit (to comply with racing rules).
If you still have questions, post a picture and it may be easier to help you.