It was revealed in The Scorch Trials that WICKED, in fact, conducted two experiments, each experiment including a different maze. The Maze Trial for Group B was extremely similar to the Trial for Group A (The Gladers), with minor differences. It is said to be an alternate, where instead of boys, girls take their place. The members of Group B escaped their maze three days earlier than the counterpart, suffering less casualties and killing more Grievers.
The Trial Edit
Everything in Group B's trials was the sames as Group A's before they escaped. The only difference is that Rachel, Thomas' Group B equivalent, was killed by Beth because there was no Chuck equivalent to save her like Thomas. This makes Thomas believe he should have died instead of Chuck.