2.5" -> 3.5" internal bay adapter

I know 2.5" -> 3.5" bay adapters exist, but do any exist that allow you to put multiple 2.5" devices in the same 3.5" bay? I'm specifically pondering replacing a single 3.5" spinning disk drive (my root disk) with two 2.5" drives (one for root, and a small SSD to put mysqld on; I'm disk-bound, and the lifetime and safety of the data is less interesting than the speed it can be manipulated at.)