I'm struggling to find a way to express the idea that it's possible that something was done before something else was done. I'm not sure if I'm just tired, but the idea is this:
In the present perfect, you would say "it has been done before". When you add "may" it becomes "it may have been done already".
In the perfect past, you would say "it had been done before". How does that sentence look like when you add "may" to it? "It might have been done before"? "It may have been done before"? Or even "it may have had been done before", as clumsy as it sounds? None of these sound particularly correct, so I'm at a loss as to what the solution here is.