Unexpected of Manage Event Type in Fusion Projects- End dated event type is allows to duplicates

An event type 'INT_REV' was used and marked for migration only, has a start and end date of 01-Jan-1951. When going into contracts and pulling up events that used this event type, then using Actions - Duplicate, it creates a new event using the event type, save and close. Now the business can go into the contract used for testing and see the new event type created for the Contract with a new Event.
When running revenue, this event will not be picked up so the user must then go into the created event and change the event type to an active event type, save and re-run revenue.