Problem when importing animation from maya

Hi Guys,

I want to make two animations be played at the same time, for example, the legs playing the walk cycle animation when the arms are playing the punch animation , for this I am using the animations layers.

It I already had done before with other model, but the model that I am using now this is not working, searching the reason for this I found in the animation window that the punch animation have keys for the legs on unity, so it overrides the keys of walk cycle animation , but the punch animation on maya don't have keys on the legs, just the arms and the chest have keyframes.

Is there a way to remove these keys inside unity or a way to unity import correctly the animation keys?

Thanks