The set name is not unique for this activity association

Hi all

We're trying to create a new consolidated plan with multiple activities but when we attempt to save on the first activity we get the above error

"The set name is not unique for this activity association".

The first Activity (A1) is already listed on a PM Schedule using the same Set (MAIN)

That plan though is end-dated, using the Effective To field.

The new plan has an effective from date > than the effective to date of the original schedule.

Is there anything else I can do in order to add this activity to a new schedule without having to update the Set Name on the new plan or on the old one to bypass the unique constraint.