No, it is not and that is a problem to come to terms with.
It dependes on what is meant by "validation".
The iru contains a 3 axis gyro triad, either mechanical platform or laser ring, but also most importantly, accelerometers. The gyro triad can only provide attitude info but the accelerometer and gyro data via some fancy math gives absolute position on the earth's surface. Integrate acceleration once to get speed, twice to get distance travelled.
There may well be cross coupling between systems that measure similar parameters. Air data info may be mixed in to the IRU to provide cross referencing, fault detection etc. For example: detection of an unexpected transient between iru and adu calculated air speed that doesn't stabilise within defined time limits, points to ?...