When replacing a HART Field device, it appeared that updating the device revision info at the DeltaV I/O card level and downloading the I/O card caused Device Manager to retire the replaced device to a Spare, add the new device to the AMS Group and transfer some device parameters such as scaling, HART tag and description to the device- the only user action being the DeltaV update and download. Audit Trail did not register these events. This is concerning, as the field device was seemingly modified "on the fly". Looking for an explanation of why this occurred. Level 1 tech support experience has not been fruitful.