Well, sort of.
If more than one user is engaged with a single enemy, the gold/exp gained from that enemy is split among the attacking players. There is no limit to how many can be attacking a single enemy. This does not apply to bosses, as you must fight them on your own.
This also means that users can snipe -- find an enemy being attacked, choose to "attack" them, but then just sit there until the other user kills the enemy. However, I don't think this is a problem, as it's fairly realistic. Also, it'd be hard to pull it off very often.
Battles will still progress individually (you attack and they attack), but the total HP of the enemy will be reduced by all participants. One person might attack the enemy five times, and other might attack once. You still split the pot.
This has required a lot of changes in the main battle script, so new bugs may have popped up.