So I was making a video simply showing the different outcomes of the Fort Condor Huge Materia mission, when a thought came to mind.
Naturally, as part of the research I was looking at the criteria for digging up Phoenix (and Bahamut ZERO), and I noted that the thing that decides whether you can dig up Phoenix, other than place excavated, Buntline obtained, and PPV post Disk 2 Midgar, is whether the Phoenix flag is on, which is turned on when either the Phoenix Materia is excavated or when it is obtained from Fort Condor.
I actually recorded all the footage for the video when I thought "What happens if I don't pick up the Phoenix Materia after completing the mission?". Turns out you can ignore it, and I went off and did North Corel HM mission and could still access the door.
So I checked the Phoenix flag: not used anywhere else. And I noted the Materia in Fort Condor is placed when a different flag is off. The flag is the "seen the Condor fly away" check, which gets turned on at the same time as obtaining the Phoenix Materia from Fort Condor, but NOT from Bone Village.
So I then played through the rest of Disk 2, excavated the Phoenix Materia, then returned to Fort Condor aaaaaannnndddd.... A second Phoenix Materia.
http://www.youtube.com/watch?v=MCRt0DCffsk
Of course it's mostly pointless. You have to wait until Disk 3 to use Phoenix at all, and you could just master the first to get a second. But it is a thing and I don't think people know about it.