Taking what it says about Troy at face value. It's a play upon her name and her meta-continuity, using the "mythological" question of Troy as a metaphor. Donna Troy exists because the writer of Teen Titans thought that the Wonder Girl in earlier Wonder Woman stories was a separate character, a sidekick of Wonder Woman, as Speedy, and Robin were to Green Arrow and Batman. When she was in fact a teen Wonder Woman who had adventures with her future self. Donna has then had several retcons, origins given to her to explain her existence. Magical mirror twin, rescued orphan, some cosmic shenanigans, etc. And with the last panel, Troy exists because of a confusion between two old storytellers who got mixed up, and she was never there in the first place.