When you do a big search in the AH (such as all Armor with no filter) and scroll down, at some point near the bottom of the scroll bar it dynamically loads more data and moves the scroll thumb back up the bar. All correct.
Unfortunately if you continue to scroll down, at some point you start seeing the same data a second time. This is quite obvious if you are using the default sorting of Price, as you get to 40g items then suddenly it is back to 20g items again (and it is the same 20g items as above). If you scroll even further it gets back to where it was when the first dynamic scroll happened and then jumps ahead to where it left off at the 40g items - so I’m fairly sure we’re seeing all the items, just not ordered correctly and with some duplication.
Thought it was worth pointing out because a misordered list also sounds like an opportunity for memory leaks to creep in.