The tag should have tire pressures appropriate for the load (weight) on the tag axle. It is not desirable to have them the same as the drive axle. Usually the tag is designed to carry only a modest portion of the total weight, maybe 6000-9000 lbs and the tire pressure should match. Excessive pressure in the tag actually reduces the weight carried on the drive axle, i.e. it lifts the chassis off the drive axle and thus reduces traction there.
I do not us Cat's Eye or Corssfire and have TPMS sensors on each tire. When cold, my duals are within 1 lb of each other, but there is some further variation as I drive. The inner dual gets a bit higher, probably becasue it runs hotter (less cooling air flow). And one end of the axle sometimes gets 1-2 psi hotter than the other, usually the sunny side.
2004 American Tradition; 2014 Buick LaCRosse
Homebase in the Ocala Nat'l Forest near Ocala, FL