I live in DC but work in VA. How do I need to file my taxes?

I live in DC but work in VA. I recently changed jobs, but still have the same living-working situation. The W2 from my previous employer states that I paid VA taxes, even though I live in DC. The W2 from my current employer states that I paid DC taxes. I was prompted to complete a non-resident form for VA and got essentially the tax I paid to VA back in a refund amount - but owe almost $3K in DC taxes. How do I know what I've already paid in DC taxes, and should I list the amount of tax paid to VA as double taxation to DC? 

 

Also, when I put in a requested refund for VA, I'm granted any value I put in (essentially) saying that I had paid that much in VA state taxes. Is that normal?