Blogger : Code for multiple google+ authorship

Try this code for multi-authorship authors
Step-1: Signin into your blogger account.
Step-2: Select Template
Step-3 : Press Edit Html button (Template --> Edit Html)
Step-4 : Paste this code where you want to add author profile
 

<b:if cond='data:top.showAuthor'>
          <data:top.authorLabel/>
            <b:if cond='data:post.authorProfileUrl'>
              <span class='fn' itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'>
                <meta expr:content='data:post.authorProfileUrl' itemprop='url'/>
                <a class='g-profile' expr:href='data:post.authorProfileUrl' rel='author' title='author profile'>
                  <span itemprop='name'><data:post.author/></span>
                </a>
              </span>
            <b:else/>
              <span class='fn' itemprop='author' itemscope='itemscope' itemtype='http://schema.org/Person'>
                <span itemprop='name'><data:post.author/></span>
              </span>
            </b:if>
        </b:if>

Check AuthorShip using google structured data testing tool

Step-1 : http://www.google.com/webmasters/tools/richsnippets