rng – Unable to update the record unless duplicates are allowed

Whenever I try to modify and save an existing registration, unless I keep the "Allow Duplicate Registrants" box, an error message stating that this user is already registered (if I am not Try not to create an existing new one). This is a big problem because, like most users, I use this module to allow only one registration per user in an event. This bug is consistent in 1.3, 1.5, 1.7 and dev versions of the module.