It can be used to express that a "situation or someone's behavior remains the same, especially when it is boring or annoying". (definition from Cambridge dictionary) So if one of your friends whom you met after a year asks, "how are you?", you could say "same old, same old". This means that your life hasn't changed much during the year, and that there's nothing interesting to tell about it.

It means the “like the usual”. Something is predictable or familiar. E.g The game is designed in the same old, same old way. Meaning: The game is designed in the usual way.