Actually, there are only two. The SGC had both the Giza Gate and the Antartic Gate until "Small Victories" when SG-1 beamed the Giza Gate aboard Thor's ship to escape the Replicators. That 'gate went into the ocean. They thought that 'gate was destroyed, but the Russians picked it up and the SGC kept using the Antartic Gate. The SGC wound up blowing up the Antartic Gate and then we got the Giza Gate on loan from the Russians. :D

I admit that I had to look up the tracking.

No new question? ;)