you can use those mediums as hive bodies, for swarm catching, as nucs, etc. you won't have to order different size foundation. use strips or foundation from the shallow supers. the bees will fill it in. you just have to be a little more careful attaching it to the frames. i use melted wax to attach mine.
free stuff is good and you'll find a use for it. i have gotten stuff in lots from folks going out of business, and with few expections, have used all of it, even stuff i had to get on the 'net to ID