Originally Posted by Skans
To my knowledge there is no such thing as dual residency. You must be a resident of only one state, and it's usually determined by how much out of the year you spend there. Drivers license and voter's registration are just "proof" of residency.
Have you read any of the BATFE advisories on this topic? Or their FAQ site? The BATFE specifically recognizes -- and states -- that someone who owns homes in two states is a resident of each state during the times when he/she is actually living in that house.