Google displaying a different site when I type info:mysite.com

And the info it displays is an other site of mine!

Actually the reason for this is obvious. I installed WP on my site A, just adjusted the settings and installed plugins and everything then I cloned it to my site B with a plugin (no posts or pages...just bare wp installation). Now Google thinks my site B is my site A!

Should I worry for this or is it going to get back to normal after a while?

Google recognized duplicated cloned contents and only shows one domain in search result .
you can't rank domain in such way and google will delete one of them .

How can Google recognize duplicated contents where the content is literally empty? What I cloned was an initial WP installation with the default post Hello World in it. That is the duplicate content?

That's really strange. To clarify: you cloned site A to site B, and now site A is gone and replaced by site B in Google? Really sounds to me like Site A is misconfigured in some way...