Is it possible to have 2 CPU?

yes it's have now on motherboard but maybe if different cpu generetion can work both.

Some Server Motherboards do have dual CPU sockets and some do use them for workstations

Try to use any xeon 26xx v3 processors and motherboards.

It is possible to have 2 CPU's in a server machine as most servers support dual processors.

yes it is possible !!!!!!

yes, nowadays anything is possible, but I believe it is better to have a powerful CPU for games and two or more for servers

I never heard of multi cpu's but I know that Laptops like the Microsoft Surface Book 3 have 2 CPU's one in the laptop itself and one in the tablet that is also your laptop screen.

Its possible, but you would not likely see the benefit in it with everyday applications. as the apps will not have been developed to take advantage of the setup

i think yo can have to GPU but i am not sure if it will be faster

Yes, there are dual socket motherboards.
And yes, they technically would run faster.