Woot a question! In the final write-up for the setting the number of different stances a character can use at one time is more limited (a single stance except for martial artists which can ultimately use up to four at a time by 17th level), but one stance feat taken two or three times still only qualifies as one stance (so having Stance of Broken Stone three times doesn't provide +3 to AC while unarmored, just +1 to AC). Essentially you've got one stances slot and multiple copies fit into that slot just fine, it's only a problem if you know more than one martial arts stance.
now you have me intrigued... I had thought about having the prof bonus but rounding up so you could have 1 2 or 3, because I was a little worried having 2 or 3 might be pretty strong when a lot of them are adding d4/d6/d8 damage to unarmed strikes. I like this idea especially since there is not a lot of feats to take.
Javelin of thorn whip.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.