I dont work at either but at pets at home to buy an animal now you have to sign an agreement on an ipad and they can search through your purchase history to see what pets you have brought from them. They also check records of animal cruelty and records of if you have taken any back or sent them into the in store adoption centres
at least thats what they do where i live! It is also pretty helpful to the buyer as if its your first time buying that particular pet then they offer help and advice and give you tips on looking after it. Ive heard (not experienced myself) that they now also phone you up a couple of days in after buying a pet, to make sure you are getting on okay with it and aren't experiencing any trouble with it