State Taxable Income Incorrect

In my specific case, it's North Carolina, but I have talked to others in other states that are having this same issue. 

 

I lived in North Carolina all year, but the stock I was awarded in CA vested, so I had CA Income and had to pay CA Tax. 

 

For ease: (Fake Numbers)

- FIT Taxable: $50,000

- CA Taxable Income: $25,000 

- NC Taxable Net Income: $50,000

 

Shouldn't the NC Taxable net income be $25,000 since half of the money I made was in CA and I was taxed? Why would NC get to tax it again?