I am sure someone will correct me if I am wrong but you should be OK as they are different flights . Are they on the same PNR ? I am guessing separate due to separate booking classes.

The problem would have came if it was las -yyy - lax and they had the same flight number and would be credited as if it was las - lax if that makes sense these are the flights with a stop off on the route therefore only one but you are on two one way flights

My experience at LAS is all American flights are in T1 so you will be fine.