Nah. Does nothing for me.

Pros:
* Geek-appeal of having 2 separate systems in the same box.
* Separation of systems lets you power one down while leaving the other running for server functions.
* Separate hardware platforms for two systems and only need to lug a single box around.
* Bragging rights

Cons:
* Security (from someone that has lived thru the heartbreak of losing their baby to burglars) – somebody steals that box from your house, they are essentially ripping you off for two computers.
* Can’t have one without the other
* Weight – you are essentially lugging the weight of 2 whole computers in that one box if you need to transport it.
* Kinda hard to install each system on its own circuit. Separate ones can be installed in completely different rooms/floors from each other
* If one side is your gaming rig, you can’t take it to lan parties without lugging that other hardware as well.

I personally like to have each system packaged in its own box and handled separately.

dual systems is quite old though, but fun to have indeed, but sepparated psu perfered

here some cases when i heard this i thught at 1st about mountain mods i think they started this dual system but it is not realy a hit to have dual systems,

AZZA 4000 arround 2012
mounainmods (custom)
Lian Li PC-D666 arround 2014

most stuff you can do with 1 system so why 2 systems if 1 system is powerfull ennough to do everything , cpus get faster, there is already build in gpu in the cpu so aditional gpu can add sepparated screens for adding a dual account on 1 computer , i always used vmare and splitted my notebook, one used the hdmi with an sepparated keyboard/mice, and the main used the notebook compartments , ofc it caused alot stress but it worked fine

i perfer indeed if a dual system to have 1 atx/e-atx and 1 mini itx/micro itx but a sepparated psu not 1, i think 1 single psu can’t be stable with 2 systems,
in the past there was coolermaster stacker witch had dual psu for some reason eventhough it didn’t had an option for dual motherboard, i have one of those cases