Hi Rick
If a user is an editing trainer for a seminar event this assumes that they are running the event so need to be at the event during the event hours.
This means that they would get the conflicting time message if they are wanting to enrol as a Learner at the same time in another event.
When an admin manually adds an attendee there is a check box that can be ticked to 'Allow scheduling conflicts' so they will be able to be added.
Regards