Remember when you vote, you are voting for Candidates in your state. This is true even in Presidential Voting for you are NOT voting for a Candidate but his Electoral Voter Nominee. Simply put you are voting for X to vote for your Candidate during the Electoral Election that takes place in December.
The reason I mention this is even if you vote twice in a Presidential election, you are NOT voting for the same person twice. In State X you are voting for Electoral Voter Y, in State A you are voting for Electoral Voter B. Y and B may be committed to the same Candidate, but they are TWO DIFFERENT ELECTED PEOPLE (WHO can not hold any FEDERAL Position).
Unless a State law Clearly says you can NOT vote in another State's Election, why can you not? If I have the Right to vote in two different states given I meet the voting requirements in BOTH states why can I not?
IF Both States says I Can vote if I lived in the state three months in the last year, I meet BOTH state's LEGAL Requirements.
Furthermore they is the "Military Exemption". Most states permit Military personal to vote even if the personal have been out of the state for years, at the same time if the Military Personal has lived in another states for the legal time set by that state why can he NOT vote twice? He has meet the LEGAL REQUIREMENTS of BOTH STATES.
under the concept of Federalism.
For a synopsis of Voting Requirements by State see:
http://www.infoplease.com/ipa/A0781452.htmlThe KEY is the term "Residence". Can someone be a Residence of two (or more) states at the same time? In an IRS case it was held it was possible for a person NOT to be a residence of ANY ONE STATE for purposes of Income Tax deductions, thus it is possible to be a US Citizen and NOT a resident of any one state (It involved a Traveling Salesman who never lived in any one state for more than a few weeks at a time). By the logic of that case, if two different state Residency's laws permits someone to claim residency in EACH STATE AT THE SAME TIME, than that person can vote in both states.
Now most states require a 30 day residence, but notice that some states do not AND THE MILITARY EXCEPTION TO RESIDENCY.
As a general Rule 99% of the Population will NOT be legally vote in more than one state but they may be exceptions to that rule.