@cgaona
You can add a basic author in Settings > Permissions that is just the combination of the two authors. That's what I do on our site. For example, the display name is "John Smith and Jane Doe", first name is "John Smith and", last name "Jane Doe", etc. Also edit the profile of that author to have the two profiles of the authors if you'd like. On the blog, it shows up as "Written on <Today's Date> by John Smith and Jane Doe"