Erm, i'd guess that they will do a little more than a single 700 will, due to the larger cache which prevents both processors in the dualie having to struggle for RAM bandwidth, so whatever a single 700 does plus a bit!
Not sure what a single 700 will do, but guessing at about 2-3 per day for 700, so i reckon 5-6 for a dual 700 xeon?
Just a guess!