Your credit union should require that the member use a restrictive endorsement – ‘For mobile deposit to [your credit union name]’.
It is also recommended that your member agreements shift liability for a second presentment of an item to the depositor if the depositor fails to use the required language. Also, check with your RDC Process Vendor; eDOC Innovations, for example, offers a service that will scan for restrictive endorsements on all RDC items on submission.