mapping domains, all domains set as primary ??

could this cause any problem??

reason I’m asking this:
http://wordpress.org/support/topic/mapping-domains-issues-wp-32

OK, so far everything is ok as I basically have it working, BUT my problem is that when I type domain1.com it goes to mysite.com/sub-directory-site1 (showing that full url)…

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IF at Domains I check Primary for each domain, it work as expected (not redirecting to mysite.com/sub-directory-site1 when I open domain1.com but actually loading the page at domain1.com)
BUT as I understand this Primary option is for ONLY one primary domain (in this case, supposedly mysite.com) this solution dosnt really satisfy me much.

sorry for the kind-of-duplicated post, but as I didnt got any replys on the former one, thought could narrow down a little my question.

thank you for an answer, Gonzalo.