intakemanifold gaskets on 1990 Chevrolet G Series Van (G20)

what is the differance in an intakemanifold gasket for a 1990 chevy G20 4.3l engine? the gasket we pulled off had 10 rectangle openings where 4 were closed off. The gaskets that we bought had 10 openings with 2 closed off. Did the part store give us the wronge gaskets? For the water & oil mixed after repair. Yes we sealed it proprely.