98 accord V6 O2 sensor help please
 

Hi everyone. I have a O2 sensor question probably basic, but Im somewhat simple lol. 1998 accord ex v6. The code I have is P0138 believe it is bank 1 sensor 2. I replaced the sensor before the cat converter and code came back. I know there is sensor right in the rear of the cat converter. I am wondering if there are any more or is there only the 2 of them. And did I replace the wrong one? I thank you all in advance.

P0138 = secondary sensor high voltage

That sensor is right into the side of the cat. The primary sensor is clearly before the cat, kinda where the pipes come together from the 2 manifolds.