“Point of View” is episode six of season three of Stargate SG-1.
The episode starts off in Area 51, where the quantum mirror that transported Daniel to the alternate Earth that was under Goa’uld attack in “There But for the Grace of God” is being stored.
Dr. (not Major) Carter and Major Kawalsky from another alternate universe (not the Earth that was destroyed by Apophis when Daniel visited it). This is a new one that has just been destroyed by the Goa’uld, and Carter and Kawalsky want to stay, as they have nowhere else to go. This Carter was married to O’Neill. Kowalsky, needless to say, isn’t dead as he is in this timeline.
With there being two Carters, apparently the new Carter will die unless she gets back to her own universe – which Earth is conquered by the Goa’uld. The idea is to contact the Asgard and get them to help.
A number of duplicates in this episode, both dead and alive. I wonder why this Earth was invaded a year later than the other two?