I'm a bit outspoken in these kinds of situations, so I might ask "how many times have you seen the client?" to the psychotherapist and then "Oh, and how many times have you seen the client?" to the OT. Then I could reflect "So, it might be that as you get to know them you can see that..." and support the weaker voice if I felt it was better evidenced. But then I'm qualified and can be a bit less tactful than you'd need to be if you were in a more junior position. But being relatively new and junior can allow you permission to ask questions. "Sorry, I'm quite new here, but I wondered how come you've formed such different opinions... how long have you known this client?" might work, for example.
Wise men talk because they have something to say, fools because they have to say something - Plato
The fool thinks himself to be wise, but the wise man knows himself to be a fool - Shakespeare