Oh dear, so many conflicting replies. We'll here's my two cents:
#1 Like Matt Nace said, better off treating both fish for ich because if you have ich, you have ich, and it is in the system not just localized to the infected fish. So to make it easier on you, keep them in the same tank with a divider like buckmasta said. Most dividers are perferated to allow for water exchange but not for the fish to get at one another. If you can, find an opaque divider as oppossed to a clear one. If the fish can't see each other, all the better.
#2 How big are your oscars in what size tank? As soon as the fish are treated and the ich is gone, definately seperate them or purchase a large tank. A friend of mine has a full grown pair in a 90 gallon tank, and the big albino still beats up upon the other tiger now and again. Make sure they have lots of large, heavy rocks siliconed to the floor so they can't redecorate but they still have territory to defend and caves to duck about in. Putting a submissive oscar in with other SA chiclids might not help matters. Jack Dempsies, Green terrors, even Texas cichlids are known to kick the daylights out of shy Oscars.
~~Colesea