they've had a long running promo where if you bring in a competitor's VISA Infinite they'll give 15K points + FYF on their Avion Infinite card.

regarding Shoppers, once earlier this year, i went in to try to use a Shoppers GC to buy another GC from their stack (Esso i think), and they wouldnt let me. I actually went to grab a GC to check, and it really did say on the back, that you can not purchase gift cards with shoppers gift cards. I simply went to a different Shoppers and they were fine with it.

it was a new thing back then, because the Shoppers GCs i had bought from Shell (was when i was double dipping Air Miles and Aeroplan at the same time) didnt say that. i dont know if the current GCs have that printed on the back, but you may want to double check that!