Maybe this is a very dull question, but,
Why do 2 speakers, from the same set (same box, brand, make, characteristics) do not sound the same ??
I have noticed this on several speakers, from really cheap to more expensive speakers (hey, i don't own $1000 speakers)
And many times one of the 2 sounds just a little clearer.. a bit more 'highs', and the other is more 'damped' ???