Actually, Hinduism wouldn't have bit of trouble with this. You can be a Hindu and some other faith with no problem.
Catholicism, OTOH, by definition requires exclusivity.
Actually, Hindus do have a problem with this. It means yoiu HAVE to proclaims yourself Hindu if you want also to be Christian. That means accept the caste system and not try to persuade caste members to get too “uppity.”