Instead of managing two different sets of fans on Blogger and Google+, you can add the Google+ Followers gadget to your blog to keep one consistent set of readers.
How it works
After you upgrade your Blogger profile to a Google+ profile, you can choose to associate various blogs with either a page or a profile. Check to make sure that that page or profile publicly shows your followers on Google+ (if you've elected to make your followers private on Google+, they won't show up on your blog when you add the gadget).
When you add the Google+ Followers gadget on Blogger, readers can add that page or profile to their circles, directly from your blog. The gadget works the same across Blogger and Google+, so the followers you see on your blog will be the same set of followers you see on Google+. Since followers of your blog are likely to share common interests, readers can connect with each other by clicking the profile images of other followers, and adding them to their Google+ circles.
Note: This gadget can be used simultaneously with the existing Google Friend Connect gadget. You can have either or both on your blog, and arrange them as you like via the Layout tab.
Add the gadget
To add the Google+ Followers gadget to your blog, go to the Layout tab and click Add a gadget.
Then, find the Google+ Followers gadget in the gadget list, and click +.
If you've added the gadget and it's showing up empty, click the Google+ tab in Blogger to make sure you've selected a valid profile or page.