Sure, we have also thougth about this fact. The problem appears when the same activity is referenced from two different places, no matter if we are talking about role-part, environmente or plays, the fact is that you have to do the activity twice.
On one hand, the activity has different meaning into different contexts. Another point of view is that the activity is the same, and you can do again this activity, no matter if it have been finished or not. That means: if you have already done an activity and it's time to do it again from another place (role-part, play, etc.) the activity is shown and you can do it again.
Copper-Core behave like .LRN IMS-LD in this sense.
