I am generally quite comfortable with any topic in therapy but something like this, for me, would be beyond what I would feel appropriate to bring up, it would feel like intruding on his private matter. But maybe a therapist would not mind.

I would ask myself the question why it is important and/or is bothering me that he has been wearing the same kind of clothes for a few weeks? Is it primarily a curiosity about him or because you feel it has something to do with you?

I agree with those posters that suggested it's pretty unlikely that his clothing choices have anything to do with you. Are you the only client he sees on those days? if not, it's not only you that meet him in those clothes. I personally never owned identical sets of the same clothes/shoes but I know many people that do - it simplifies life and style for those that do not care much about fashion/variety and prefer to stick with a few pieces that they like and find comfortable.

This is not to sound invasive, but from your various posts, it sounds like you often speculate and imagine things about your T and not really ask the question why you imagine these things? Perhaps that would be a productive way to look at your fantasies and why they come up, focus on your side of it?