Hosting two Gmod servers on one machine

How would I do this? Is it possible to use 2 servers on different ports?
And what ports can I use?

[editline]5th September 2013[/editline]

I use 27015 for my main server

You can really use whatever ports you want.

Does it show up on the Server Browser?

Yes it does you can use 27016 for one server and 27015 for the other and you can keep making more servers if your machine can handle it.

[editline]5th September 2013[/editline]

Oh and in the start up you need to do +port 27015 or what ever port you chose.