Thanks for the compliment BigBas, but I missed your point - that all John Doe should have the same number. I can hardly blame the IRS and late night for diverting my focus (it's due tomorrow here). So to do what your meant, I would basically use the same formula.
//Ola
Code:
=IF(COUNTIF($A$1:A1,A2)=0,MAX($B$1:B1)+1,VLOOKUP(A2,$A$1:B1,2,0))