If you ask me, I dont see why Jet should have any problem with folks having multiple CC's from different banks it partners with.. Co-branded cards are there for the mutual benefit of both the bank and the airline and other than the bonus miles which some of the folks would get and which I believe is reimbursed by the bank to a large extent..But then , banks do frequently give promos to attract new customers hoping that some of these new customers will continue with them etc etc..