That's sort of a tricky question.
The fact that the speakers are timbre-matched probably wouldn't signify much one way or the other.
However, speakers all of the same model and manufacturer should be quite closely matched. The phase response of a speaker is determined by the drivers, the design and type of crossover used, and even the cabinet tuning has some effect on it. I would figure that speakers of the same model from the same batch would be
VERY closely matched, you might or might not see very slight differences over different batches (especially if the particular model is produced for a very long time). Next, speakers of similar models, with similar drivers, and from the same series (like the center and fronts form a certain model line) would also probably be pretty close.
Anything beyond that is a bit of a guess since even one manufacturer may decide to use very different crossover designs on different models, and they can be wildly different between manufacturers, even on speakers that are superficially similar in design, and that sound much the same (like three way speakers with dome tweeters and 8" cone woofers).
Luckily, it's probably not critically important that different sets of speakers be that closely matched as long as the speakers in each symmetrical pair (front mains, or surrounds) are very close. The biggest effect phase response has is on imaging, and there just isn't much critical imaging between, say, a left front and a left surround. (Things like frequency cancellations due to phase differences will probably be less noticeable than frequency response aberrations caused by room placement and such.)
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Thanks Keith it is nice to learn something factual and not repeated mis-information and the application of a filter affecting phase certainly makes sense . I have a question - Does having a set of timbre matched speakers help to keep them in phase over varying frequencies or is there still significant variation?