M-L Summits: Why Bi-Wire?

If the M-L Summits carry on-board amps for the woofer section, why do the speakers have two sets of binding posts? It's not as if you can disable the on-board amp, right?
One for the midbass and one for the tweeters? I'm guessing it's the same reason you can tri-wire some speakers.

According to the Manual the second set of connections for the woofer section is there as a convenience for users that may have bi wire cables.
Yep, what Kenscollick stated is what the tech department at ML stated as well...
Thanks for the replies! I have to admit that my first thought upon reading Kenscollick's response was "oh come on ... what a crock...." But then I thought about it some more and it made perfect sense, really: some of us have single bi-wire speakers and it makes sense to provide "dummy" binding posts for those extra connectors. Very nice. Thanks again!