Bwahahahahaahha!

not long,... id have to say around a minute.

That is of course if this was some bizarro real life thing, in the game the question would be more like so: How long would 2 cyberdemons last against NoobWantsHacks?

wow, i tried this, what weapons can we use?
(pssst! i used a plasme rifle and rocket launcher, they both died!)

Wouldn't be so hard you know. In Grosse, the one Cyber Demon is quite easy to defeat, although it takes a while! I dunno, if the room was big enough with enough pillars then it shan't be that difficult. But things can't be too close because of splash damage.

Can Cyber Demons fight each other?

not very long D: 1 second? :thk
I'd run away screaming or sommin..

I bet I could win with 100 health, if the level was really small I couldnt go for long though.

depending no the room... if it was a big one... i last until they die... small room about a min... or 5

i play the iron of sin on doom and i went to the top and i saw 9 CIBER DEMONS and i bet 8 befor i dided and i didnt have god mode or eny tin i just had all my guns so for me 2 wold be esy for me and im only 10!!!

Considering they have to stand still to fire, it's not that difficult at all. On one particular fan-made megawad (30 levels) there's a level where you need to fight two at once. I played it on multiplayer with my brother, but due to a glitch my brother spawned outside the map with no way in. Multiplayer maps almost always have more monsters on to accommodate the fact there's more than one of you and the creator had set there to be 5 Cyberdemons in a circular arena with a hexagon of pillars (imagine a hexagon, a pillar at each corner basically) and all around the outer wall are imps. I took them all down on Ultra Violent without dying. I don't think I've ever circle strafed as much as I did on that map.

This is my version of it:

i would kill one of them and die after he died XD