Separate call recording callers voices and change pitch

Hi!

I have a call recording where two callers are speaking. I need to change one caller voice, so it won’t be recognizable. And later for that I think I need to change the the pitch to get the effect needed.
But as I have tried and since I’m new to audacity and google also did not give any results as needed, is there a way for separating callers voice’s so when I change pitch it won’t change it for both of them?

Thank you in advance!

The recording is placed as you said L and R, when one caller speaks the L volume moves and if another one speaks then R one moves.

Changing pitch is reversible: will not provide anonymity.

Have another person , or speech-to-speech AI, say the words of the person whose identity needs to be concealed. (You could add pitch-shift just for old times’ sake).