State tax filing

I'm not sure if my employer's data is accurate for when I became a resident of NJ.  It may just be based on an estimated move date, not the actual date I moved.  Can I just ignore that amount on my W2, and calculate the NJ portion myself based on my own math?  Will this create a problem if NJ is receiving a copy of my W2 from my employer, which would show a different amount attributable to NJ?