There's also the limit break meter and it charging slower with duplicates. I think you can still hit it with a dupe but that depends on people not dying and that's something I see all the time in farm parties.
Oh well no reason to step in that place again. Got the mount on my 12th try which is surprising for me when most of the time it takes around 150 kills on average to get one. Also got 95th percentile on that fight on my Red Mage which I'm pretty proud of too considering I'm only 349.