Exactly
And from the info available, it would appear that how the Power is increased would play a part. If the FOHE has ice in the Fuel passages, care must be taken to avoid a sudden increase that disturbs the ice upstream, allowing it to drop and block completely the exit of the Fuel passage from the FOHE. The increase commanded by the A/T's produced large EPR's with accompanied Vibration; the FOHE is mounted on the Fan Shroud, after all, and full chat creates monumental vibration and acoustic energy. This might have shaken loose enough ice to pack up the exit, causing Rollback to ~1.15~. Again, the similarity of system performance would "defeat" the "expected" isolation of each engine from the other; at some point, systems are identical at the end of the pathway.
AF