I can't tell you for sure, just give you my opinion:
(1) viewing as an affiliate promoting and then not getting credit, because you use your own id it is not good, right - but to be honest, if someone does not want to give you credit, there's nearly always a way, these are bad customers anyway, you'll not be happy to have them on your list
(2) viewing as the seller selling the product I would say, if they don't say definitely no, they will certainly allow it - the reason: it's business for them & means more money, because you are more often buying, "because" you get a discount (psychologic selling)
So to speak, it's not nice, but also you cannot prevent it really - I by myself would not "kick out" an affiliate, if he is just buying from him-/herself - it's paid business and like said, bargain hunters will always get their bargain or not buy - my point of view. End
