." >> reporter: miami preschoolers jia sarnicola and zuri copeland say they're not best friends.ple years ago, they say they're closer than friends, closer than mere sisters, even. in fact, jia and zuri truly believe they're twins. >> oh, yeah. >> axelrod: ashley and valencia are their moms. >> they will tell you that they are twins and they have a long list of reasons why to back it up. >> reporter: to them what makes a twin? >> similarities. >> look, come here. >> reporter: for example, the girls say their birthdays are practically the same day, and the obvious physical similarities. so what am i looking at here? >> the same height. >> reporter: oh, 'cause you're the same height. clearly twins, which is why they also insist on matching outfits whenever possible. so far, ashley and valencia have indulged them, but they also recognize there is some bitter to this sweet. >> you know, you're happy for a few seconds, and then you become sad because they have to grow up. and then society takes over. >> reporter: indeed, society already tried to take over. zuri and jia were at a birth