In Games

Why are the arcade versions of NES Games have "VS" in the name? Was there a possibility to play against each other simultaneously? And if yes, is it possible to simulate that with an emulator?

Yes, VS games are games where to play against a oponent,
a friend on controller 2 or even the computer.
They are modified versions. Recently I bought VX Excitebike
for Famicom Disk System, where you can play up to four
players or then play against three computer bikes.

THIS IS REALLY HOW THE FIRST Excitebike needed to be!!!

And, about emulating this feature, I really don't
know about it.

Cospefogo.

So, how is it possible then to play "VS Super Mario Bros." against each other? I played it on FCE Ultra, but there was just the normal 2 player mode like in the original "Super Mario Bros." where it's the second players turn when the first player loses a life.

I don't think so.
Never tried to play this VS Super Mario Bros.
My only experience until the moment is with VS Excitebike!

Cheers,
Cospefogo.