If the 2 Ufers were tied together in a compliant fashion, either a 30" lap for #5 (48x) or a 4ga jumper they are being used together. I would say if it was easy (AKA "available") they both need to be used but I wouldn't go to war over it..
The rebar stubs up a few feet away from each other, there is a continuous piece of bare copper connecting both stubs to the main disconnect, there is no overlap between the rebar in each footing as one was poured in 1993, & the other in 2011, the Ufer in the 1993 build was never used as the panels had a ground rod as the electrode & nothing was changed then, but decided to have the Ufer since the steel was being put in the footings.
