3 heroes/supremacy team. Cheat or glitch?

Since the summer, I'm seeing a constant glitch/cheat in Supremacy matches where one of the teams can choose 3 heroes at the same time. Even though Supremacy is locked to 2/team, it's not a rarity that I see Yoda, Obi-Wan and Anakin at the same time - sometimes, even every 4 hero. This ofc gives the team a huge advantage. At first I thought it's a glitch, but it's very suspicious how it always happens for the enemy when they're getting pushed back - especially when they have high or max-level players in greater quantity. Have anyone else seen it, and could answer what it is? A random bug, or just maxed out sweats looking for an easy and unsuspicious way to cheat?