Posted By: 
John Moranah, 1971 topps, my favorite subject.  I think I can help out here.  IMO 12 cards are double printed in the 5th series (the 5th series CL was printed on the 4th series sheet so it's a dp too).  They include Willie Mays, Tony Perez, Willie Davis and Norm Cash.
As you mentioned, a true uncut sheet is 264 cards.  Here is the left half of the series 5 sheet, 66 different cards printed twice:
![[linked image]](http://i133.photobucket.com/albums/q66/jmoran19/71series5a.jpg)
Here is a partial sheet of the right half before the black ink was applied, it's the only one I've ever seen:
![[linked image]](http://i133.photobucket.com/albums/q66/jmoran19/71series5half.jpg)
I also have a copy of the OPC 5th series sheet.  
![[linked image]](http://i133.photobucket.com/albums/q66/jmoran19/71series5opc.jpg)
Excluding the expos that were moved up into the earlier series, the cards were printed in the same row/column as the Topps version.  The bottom 6 rows on the OPC sheet match the middle 6 rows on the left half of the Topps sheet (first picture), therefore the top 6 rows in theory would match up to the Topps right half.  As you can see, this would make the row with Perez and Willie Mays the dp's.  
John
P.S.  I made a mockup of the partial sheet, LMK is you want me to post it as well.