Sonically matched speakers

What is meant by a sonically matched pair of speakers?
The sound the same or, if you are comparing them to others, they sound alike.

Sonically matching is especially important in home theatre where you want the centre channel to be "voiced" the same as the two front speakers. Otherwise the fact that the speakers sound different will draw attention to itself and take away from the home theatre experience.

It's an interesting notion and one that doesn't get much attention. That is, how difficult it is is for a speaker manufacturer to produce instances of the same speaker model that actually sound the same. I read a quote from Ken Kantor somewhere that went something like this: "any one can build one great speaker, getting the other ones off the production line to sound like the reference is very hard."