Generally speaking yes the more the better...however you want to only run 1 row for 2 reasons...first diff rings are not flat. Because of the way they are punched out they are slightly coned so the inner row and outer row won't make contact at the same time and you will be effectively only running on 1 row. There are rings that have been flattened through sanding or grinding but then you run into the 2nd issue...the rings flex. Because the diff hub and axle hub do not go all the way out to the edge of the diff ring it doesn't support the whole ring so when pressure is applied at the outer row of diff balls the rings flex again causing them to cone so running 2 rows again doesn't work as well as we'd like.

I think if someone makes a diff axle and hub that fully supports the diff ring and we run a perfectly flattened ring set then running both rows would work nicely.