I looked into this before I ported from Koodo to PM.
There are MANY posts on both these forums and elsewhere that say you should not use the same email address for both accounts. They both use the same Telus backend, and there are potential problems when you use the same email on both accounts.
I switched to a different email before I ported, then changed the email once I had activated.
The fact that your 1 out of 3 lines (with a different email) is eligible should suggest this remains to be true.