Essentially, you have to know "what's going on" when your employer gives you a wishy washy W-2.
What state are you in? What city do you work in and what city do you live in? Typically two separate box 19 entries means tax was withheld for both your work city (or county) and your residence city. Or, your worked in two different cities. If you don't live in a city/county with an income tax (and don't have to file a resident return), then it doesn't matter what's in box 19; you can add em together (if you itemize deductions, it's only used for the local income tax deduction, on the federal return).
