I have two accounts that I wish to have associated with my Google+ profile. Meaning that I would like to be able to sign into either account, and have access to the same Google+ profile. Is this possible? And if yes, how?
No. Each Google+ account is tied to a Google Profile account, which can have only one primary email.
There's a nice work around listed here http://socialtriggers.com/connect-gmail-google-plus/
Considering G+ allows you to add people to different circles (e.g. work and friends) then it makes sense that different emails (e.g. firstname.lastname@example.org and email@example.com) should both feed into a single G+ account.
They'll come to their senses soon enough.
Until then, we need work around it.