Hi Ayiza, I just wanted to point out some things with the post that might cause some confusion.
The wording sounds like you have to hit the unique table with a 1/53 and then a get 1/500 to get the pet so your chance is 1/26500. I assume it's actually a flat 1/500 per kill?
Also the math for two players appears to be incorrect as 1/53*2 = 2/53 not the 1/106 implied.
I made a lil edit to the post a minute ago RE: Nexling as it doesn't require hitting the unique table first.
I can't comment further on the math side of things sorry. I've been told it's correct by the devs!