13th Anniversary Bosses - get loot multiple times per boss

So this works in a similar way to how the Greater Invasion exploit worked - if you start fighting a world boss for the event (Say, Kazzak) on your home realm, tag it, and then join another group through the group finder tool on a different realm, you can tag the boss there as well, and get loot for both kills. The most I have managed to get is 4 loot chances (got 2x loot, 2x gold). It seems that you only have until the first instance of the boss that you tagged dies to add 'extra loot chances'.

This seems like it could be really useful for getting extra chances to farm rare transmogs you want, like the 1H sword, etc.