Grats to all those who have cleared both 16(NM) but curious as to why the OP has a SS of a dead 16 normal mode Karagga on his webpage instead of the 3.9m hp Karagga that's in NMode?
It's a well known documented bug. Occasionally the dead mob will revert bag to the normal mode HP after death which is why most confirmations require a screenshot of loot or at a low percentage of the bosses health. Even in those scenarios if someone wanted to lie about it they could surely get away with it. We've had guilds previously claiming Bonethrasher prenerf kills with no proof and others with exploited kills, in the end it doesn't really matter so long as you enjoyed the fight.