And THAT said, my heater is still 32 years old and never had more than one anode.:P
I was in a hurry when I posted this. I wanted to elaborate a little. Larry is technically right, naturally.
We do know that anode protection doesn’t go everywhere. Steel nipples will rust to ruin even though there is a functioning anode in the heater. But most heaters sold have one anode and if you replace that from time to time, they do just fine. I wouldn’t let the two-anode thing sway me from buying a one-anode heater if all the other specs look good.