Why have you created 2 distinct accounts?
And I would very much recommend you never ever to post personal data like a mail address in an open forum, it's an invitation for spammers to harvest them.
Now to the problem you created:
If you attach a (new) BOINC to a certain, already existing project account, you give the according email address and password.
If you somehow managed to either create a new, unrelated account with a wrong adress or attached to such one, detach BOINC from the project and reattach with the right data.
If you want to change the email of a "wrong" account with the right address to that of another existing one, you first have to change the right address of the wrong account to something nosensical, like firstname.lastname@example.org, in your account settings. Then log into the other account and change it to the desired address.
Gruesse vom Saenger
For questions about Boinc look in the BOINC-Wiki