Or rather how do people know about both kill screens? If by definition a kill screen is an unbeatable screen, than how is it possible that people even know about the second one? Is it hackers? Is it just hypothetical? Or is the first Kill Screen actually possible to beat?

Right, so I have also been thinking about this. Maybe I am being stupid here. but why level 85?
 
So, the timer is calculated as so 
 
bonus = 100*(10*(level + 4))
 
and the 10*(level +4) part works modulo 256 due to the 8 bit counter (this is where I might be wrong). Which is why at level 22 we get
 
10*(22 + 4) = 260 = 4 mod 256.
 
so the bonus timer will be 100*4 = 400, resulting in the kill screen.  So where does the value of 85 come from as being the other kill screen?
 
10*(85 + 4) = 122 mod 256   and   122*100 is definitely bigger than 8000, resulting in just having 8000 as normal.
 
Here are the other levels under 100 which have timers less than 8000 in format [level, bonus] 
 
 [[1, 5000], [2, 6000], [3, 7000], [22, 400], [23, 1400], [24, 2400], [25, 3400], [26, 4400], [27, 5400], [28, 6400], [29, 7400], [48, 800], [49, 1800], [50, 2800], [51, 3800], [52, 4800], [53, 5800], [54, 6800], [55, 7800], [73, 200], [74, 1200], [75, 2200], [76, 3200], [77, 4200], [78, 5200], [79, 6200], [80, 7200], [99, 600], [100, 1600]])
 
48 seems like it would be the next kill screen

 Please do tell me I am an idiot if I am but there is no need to let me know I am sad, I already know.

The game has levels, and each level is split into 4 stages. The first screen of level 22 is stage 85. So there's only one kill screen.
 
(I'm not a DK expert, I'm just going by the wikipedia page)

@Jerusahat 
Duh! thank you... I have never played it and made a mistake.
 
Thank you again :D