same email for multiple zohocrm accounts.

same email for multiple zohocrm accounts.

I have a company (one email address) that consists of 2 divisions and both are supposed to run zoho CRM.  It seems I cannot use the same id to single sign on to each company ?  makes no sense.  especially since I intend to have about 8 of these divisions on zoho.  I would have to create a email address for each company ???. wierd and un workable of course.  any ideas  ?