Option to allow multiple registrations per contact

Several performing arts organizations are using CiviCRM for ticket sales, and in this use case, it's desirable to allow a single contact to have multiple "registrations" (ticket purchases) per event. Someone may purchase tickets and then decide later to purchase additional tickets for the same performance.

In the event "online registration" configuration tab, it seems that checking "allow multiple registrations from the same email address" should enable exactly that, but that check box apparently only works in combination with the "register multiple participants" option.

I've created a patch that makes "allow multiple registrations from the same email address" to work on its own, so that a single contact can register multiple times for the same event – or in this case purchase tickets multiple times.

Patch file is attached.