Keep them separate in their own crates. The older one may not want to put up with puppy play in a big crate. When crated mine are always separate unless they are at the kennel, then they are in the same pen because Becca is not fond of the kennel.
PS, basenjis don't like being woken up much, and one dog annoying another who wants to stay asleep might result in a fracas in a confined space; never a good thing.