Well, you've actually answered your own question
It's a Titan X, so you should be able to SLI it with any other Titan X. I'f you'd like to know what brand and exact model it is to have them look the same, you can just open up the side panel of the case and it should tell you on the card itself, otherwise post a link to the PC you bought and, I may be able to tell you.
There are other vital things you need to find out though.
-Whether the power supply can power two cards or not, especially in the case of Titan X's where you're going to need a lot of power
-If there's room for a second in the case
-If the motherboard has a second GPU slot
It's also worth asking, do you really need it? If I'm not mistaken a single Titan X should be overkill in most use cases for a while to come.
Posting your specs would be pretty helpful too. If you don't know them run this program https://www.piriform.com/speccy
and take a screenshot for us.Edited by dragneel - 2/24/16 at 1:19am