I think his rating is either randomly generated or very low, I just won a game against him, and his accuracy was 63.4 percent with an estimated rating of 550...
Duo’s rating

I think it is random also that is why they made the rating "?" it might be an adaptive bot which explains why you can be beating it and it will make a comeback and how it beat gotham chess but was beaten by someone with 1200 elo

I think his rating is either randomly generated or very low, I just won a game against him, and his accuracy was 63.4 percent with an estimated rating of 550...
You played a 'safe' opening and he wasn't as strong

I would estimate 2400 because he beat gotham chess once and lost once,
He lost because gotham played a 'safe' opening the first time and a 'not safe' opening the second time

I don’t think he is 2200-2400 as so many here seem to believe. I drew against him multiple times and even had completely winning positions in some games, I just wasn’t able to convert them. Now I know some will say the fact that he didn’t allow me to convert a completely winning position shows how strong he is, but I don’t buy it. A 2300 will NOT have a -7 position against a 1700 like me, multiple times. I really believe his rating changes as he plays. Most of the time his opening is okay but not amazing, starts picking up in the middle game (if I haven’t got a better position yet) and wipes me off the board in the end game.

I still think the rating is randomly generated, it's the only hypothesis that makes any sense...
somewhat agree
I would estimate 2400 because he beat gotham chess once and lost once,