You still need all the physical space that two PCs require except for the box which is only a small part of it. You still need all the peripherals for two people and once the 3060s are in it the power difference will be negligible between one or two PCs. On top of that you have all the inconvenience and problems that using in multiseat brings. Network gear is dirt cheap and maintaining two PCs is less hassle Vs this too.
Personally I think at the end of the day you’re better off with two PCs even if the second one is a cheap second hand one. Especially since I assume the GPUs mean they’re planning on gaming on it.