If I am not totally wrong the "read list" of a gallery chat was meant to prevent the user who is on that list to request access again.
Sorry to say that, but you are totally wrong :) That certainly is not the point of the read list, it's merely a side effect. Granted, for public rooms (i.e. not the private moderator rooms), that's pretty much the only effect of that list, so I see your point.
Anyway, this was working for the most part: When a user on the read list clicked the "request access" button, they remained in the read list (and did not get moved to the "has requested access" list). So nothing really happened.
The problem was that internally this "nothing happens" was considered a successful access request, which is why a) the user even saw the "request access" button – after all, it could cause a successful outcome – and b) the room owner(s) were informed that "User X has requested access", although from chat's perspective, they really hadn't and couldn't.
This is fixed now.