Section 3--116. Instruments Payable to Two or More Persons. An instrument payable to the order of two or more persons

(a) if in the alternative is payable to any one of them and may be negotiated, discharged or enforced by any of them who has possession of it;

(b) if not in the alternative is payable to all of them and may be negotiated, discharged or enforced only by all of them.