W2 Withholding for wrong state

My sons employer listed his school address (North Dakota) and not his permanent address (Minnesota) on his W2.  The employer paid state taxes to ND and not MN as they should have.  He only had $1,300 in wages and $6.00 of state withholding if that matters.  I am unclear as to how to handle this.  Do we need to file with both ND and MN?  He does have one other W2 from another employer that has his correct state and state withholding.  Any help its greatly appreciated.

 

Thanks