i gotta tell you, I think the "Mavs have the Spurs number" thing is a bit of an over-statement. There was a razor thin difference in one series four years ago where the Spurs were actually winning Game 7 in the closing seconds before an all-time dumb move by Manu fouling Dirk on a layup while up 3 and last year, beating a Manu-less Spurs team doesn't really show much of anything. It's been proven throughout the years that as Manu goes, so go the Spurs.
Really, what you have is the Mavs haven taken one series from them, by the skin of their teeth, four years ago. That doesn't say to me "has someone's number". Do they play them tougher than the Suns? Sure. But that's not saying much considering we're they're complete and utter bitch.