Clintons 2006 Tax Return Question?

And following along the strange twist line - if you look at the 2006 return, the amounts on line 65 ($4,642,911) seem to include the amount in some fashion from the 2005 return of $942,911 which was listed as a refund of overpayment but appears to be included in the estimated payments for 2006 ???
Submitted by David Henry CPA