Colonists keeping accidentally killing other colonists

Idk if it’s my luck or if I’m not suppose to do this, but whenever I draft my colonists to fight raids, they sometimes accidentally kill my meleeist. Like and this happens oddly more times then I would think would happen. Idk if that’s just the way the rim goes or if I’m not suppose to send my meleeist out when my guys are shooting. Which I feel like defeats the point of having a meleeist to distract key enemies