Permit more than one registration code per registration type.

Currently there is only one code allowed per type. For some events, I may have registration categories for "vendor" or "speaker", who all share the same code. If I want to limit the number of uses per vendor, there is no way to do that without setting up multiple registration types per vendor, which gets unwieldy (and ugly) very quickly.

As a use case, I may have two vendors with one entitled to bring four participants and one entitled to bring two participants, with nothing preventing either from adding more than they are permitted. Instead, allow me to set up a registration code per vendor with a limit on how many they can bring.
This could be combined with another proposal “Discount coupons for event registrations” which has been an outstanding request since 2008 so that instead of setting up multiple registrations, I just offer different codes that would be limited by number of uses. (See https://forums.wildapricot.com/forums/308932-wishlist/suggestions/8825629-discount-coupons-for-event-registrations)