It would be nice to move to Data Pump and not use the older version. The issue is that the OID identifier is already used. You need to import it and tell import to ignore OIDs. I don't know how to do this in the old exp/imp. In Data Pump, you would use this in your impdp command: transform=oid:n
There is a TOID_NOVALIDATE in imp, but I can't remember what it does.