The Ten Beta Testers Project was to reveal the existence of the Ten Beta Testers.
Weiss had always proclaimed himself as the strongest amongst other beta testers. So, it would make sense if there were other nine beta testers in Blue Star, showing up and revealing themselves due to the otherworld invasion.
Of course, the other nine Beta Testers were just Weiss' alternate accounts. Or more like, they were his creations who had the same power level as him but weren't as strong as him.
In the Player Hunter Application, Weiss had already reserved the first ten spots for himself as well as the other beta testers. So if players were to be invited to become a Player Hunter, they would have the codename "Hunter #11" instead of "Hunter #02".
That would further prove the existence of beta testers. After all, beta testers had access to the games before the game was released and published.
