You were lucky then, ltr, because Adobe even warns about this in their own material when you go to make the email address change. I purchased books from Kobo using my single account and two different ADE accounts. Kobo staff had to "fix" things on their end so that all of the books I had purchased were linked to the same ADE. This was because the ACSM's for the book were attached in different ways depending on the account email address.
See:
http://forums.adobe.com/message/2672054