[SIZE=2]I really don't think there are enough games on the PSOne that support that.Games such as the Point Blank series are turn-based and so one gun would suffice for most-the arcade portion of the games can and does use 2 guns for two players.From what I can tell the PSOne Time Crisis games are one player only as well.
You may be better off getting another game instead of a second GunCon.If you plan on having friends over for Point Blank a fair bit,though,go for it.[/SIZE]