I don't think that including twins would make the story typical in any way... The way she's introducing it by little hints from almost the first page actually makes her one hell of a plotter in my opinion, it was developed with such subtlety, she deserves recognition for that.
If they said Ciel was doing bad things and *tan tan chaaaaan* evil twin appeared, then yes, I'd consider it cliche, but it's not like that. You really think that *tan tan chan* the supposedly dead person is actually alive (or at least around) and plotting would be less typical? It's more usual (typical) than the twins thing itself, being objetive.
The important thing is how a story is constructed and told, more than it being something new under the sun (because there's NOTHING completely new in this world), THAT (the way it happens) can make a simple story a piece of art.
A typical development makes a story typical, not a particular event through it.
... I'm sorry for the long long text... ^^'
It's okay, I understand your point of view :)
I suppose Vincent being alive would be very typical too, but I really don't want this manga to have any of the usual cliches, so I hope in the next chapter we'll see something completely unexpected
Twins as a plot twins have been used way too many times - I started reading this because it was different from everything else, I don't want it to become typical!
And, seeing as there are demons, shinigami, dead coming back to life and everything else, there might be some supernatural explanation...Maybe Vincent Phantomhive's spirit is still somewhere out there?