So the house panel has a direct connection via a GEC to the house ufer? And the detached garage has its own ground rod(s)?
But in addition there is a 'GEC' going from the garage panel to the ufer, going through the same conduit as the feeder to the house?
I can see only one potential problem: is the GEC bonded to the EMT or RMC at _both_ ends of every run? GECs can be subject to extremely high _unbalanced_ currents, and the inductance caused by the steel tube is enough to cause a serious impedance. The GEC needs to be bonded at _both_ ends of the tube in order to permit current to flow in the tube itself. See 250.64(E)
-Jon
