Word for two things that are opposite yet the same

Is there a word or short phrase that describes two contrasting ideas the ultimately end up the same? Like two ends of a spectrum that can wrap around? I'm using it to describe two foils for a character that ultimately end up being in the same boat.

This could also refer to examples such as Fascism and Communism, where the ends are very similar, but all other aspects are entirely different.

Probably the most common idiomatic usage for OP's context is

two sides of the same coin

The Cambridge Dictionaries Online definition is...

If two things are two sides of the same coin, they are very closely related although they seem different

But personally I prefer this one from Yahoo Answers...

It means that the same person or subject or idea can be viewed two different ways.
[emphasis mine]

In OP's specific example, several hundred writers have in fact made the point that Fascism and Communism are two sides of the same coin. They mean both are oppressive/totalitarian regimes. Much the same idea is eloquently put by George Orwell in the closing words of Animal Farm...

“The creatures outside looked from pig to man, and from man to pig, and from pig to man again; but already it was impossible to say which was which.”

There is a "figure of speech" that may fit:

I'm damned if I do and damned if I don't.

There is Catch-22 also:

(idiomatic) A difficult situation from which there is no escape because it involves mutually conflicting or dependent conditions.