This isn’t the only time that Palpatine has tricked Darth Maul into believing he’d been replaced. Maul’s final test before attaining his Sith Lordship had him survive being hunted by assassin droids in the Outer Rim for a month before dueling Darth Sidious himself. Sidious claimed that Maul had already been replaced by another aspiring Sith, leading Maul to attempt to kill his master for the first and apparently only time in his life.
The Star Wars Legends continuity’s Darth Maul is an atypical Sith Lord for several reasons, with one being that he became a true Sith while Palpatine was the apprentice of Darth Plagueis, breaking the Rule of Two. Furthermore, Darth Maul was uncharacteristically loyal to his master, while most Sith apprentices are constantly plotting against the mentor. Although Maul struck out against Sidious the first time he’d been tricked, he doesn’t respond this way to Palpatine’s cruel test in “Marked.” This shows that Darth Maul, despite having a shorter history in the Star Wars Legends continuity, stood out among other Sith Lords due to his sheer loyalty to Palpatine.