when pairs are involved, only 1 counts, so you didnt have a2344 you had a2348. So if you had aa in your hand and there were the other 2 aces on the board you would just have 1 ace for your low hand not aaaax.
ur low was counterfeited when u paired ur 4 as it put a better low draw on board so ur opponent made a the 2nd nut low with A-2-3-4-6 whereas u had A-2-3-4-8