Are you referring to this?I understand but USC 18 922 says "purchase or otherwise obtain" which you are still doing
(5) for any person (other than a licensed importer, licensed manufacturer, licensed dealer, or licensed collector) to transfer, sell, trade, give, transport, or deliver any firearm to any person (other than a licensed importer, licensed manufacturer, licensed dealer, or licensed collector) who the transferor knows or has reasonable cause to believe does not reside in (or if the person is a corporation or other business entity, does not maintain a place of business in) the State in which the transferor resides
The best I can tell, the interstate weapons clause is to prevent the sale of a firearm to individuals that are residents of other states, not for two residents of the same state. I am rather curious of the subject, so if have a different US code that prevents the transfer of firearms to two individuals residing in the same state, then please post the code.