Hi Paul, Bill has seen a lot more Amel's than I have, but for what it is worth, on my SM 53 the anodes always seem to erode equally. Knowing that the anodes are part of an electrical circuit I am careful to always clean the bolts, and the installed anode contact areas and assure adequate torque of the bolts (not overkill so as to strip things but snug). As long as you are seeing some anode erosion then you are probably safe but at your next haul out it would be worth checking the continuity (resistance) between each anode bolt (i.e. side to side) and between each bolt individually relative to the cluster of bonding wires at the bilge bonding strap.
Basically I would continue to monitor this and diagnose further during the next haul out.
Gary S. Silver
Amel SM 2000 #335