Personally, I would never crate two dogs together, even if they absolutely loved each other. I've read so many horror stories about dogs killing the other after being crated together, whether it's accidental or on purpose. Putting them in such close quarters and closing the door, especially when you are going to bed and won't be able to supervise, is just a recipe for disaster.
That said, dogs can be quirky and can also deal with some things if it gets them what they want. For example, one of my older dogs would rather not cuddle with the younger dog, but if she is on the bed and he comes up and lays with her, she won't move because she wants to be on the bed. Your older dog must have decided he likes the younger dog's crate for whatever reason and is willing to deal with the younger dog. Or, maybe they're just getting used to each other finally - who knows!
That said, dogs can be quirky and can also deal with some things if it gets them what they want. For example, one of my older dogs would rather not cuddle with the younger dog, but if she is on the bed and he comes up and lays with her, she won't move because she wants to be on the bed. Your older dog must have decided he likes the younger dog's crate for whatever reason and is willing to deal with the younger dog. Or, maybe they're just getting used to each other finally - who knows!