How can i make my gun have two different animations

Ok so I am making a First Person Shooter game with unity and I have an animation on my gun hand which is a parent to the gun that makes it so that when the player presses the left mouse button the fire1 animation plays but i want to also make it so when the player presses LeftShift and W at the same time the gun running animation plays but when i try to import another animation into the inspector for the hand it says that there is already an animation in there so how can i make it so both animations can be triggered?