You asked about substance. I gave it to you.
If you wish to talk about what people call themselves, I give you the former Democratic Republic of Germany, which was neither democratic nor a republic. I give you the People's Republic of China, which doesn't really belong to the people and is also not a republic.
Oh, and I am a Republican. For practical reasons, concerning primary elections in PA. Yet I doubt you would consider me a "real" Republican, and frankly, I don't consider myself one either.
You can look at people and their organizations for what they say and do, or you can rely on taxidermy -- oops, I meant "taxonomy". Only one of them will give you a living picture.