I’m not sure if there are Y connectors, but you can purchase switches that will allow you to select one optical input or another. There are some very inexpensive mechanical ones on the market.
I bought one a few years ago to hook up my PS2 and Xbox to a single optical input on my receiver. It's marketed as a splitter but I use it in reverse with no problem. It's like this one here: http://www.trianglecables.com/pof-810.html