How do I see who liked your Facebook Page?

If you are an Admin, You will be able to see Who has liked my Facebook Fan Page. It is an easy task to do, you just have to follow the given below steps.

1. Login to Facebook account (as yourself)
2. Using your Facebook Page (You should be Admin, otherwise you will not able to see who liked your Facebook Fan Page)
3. Click on “Settings”
4. Click on “People and Other Pages” link
5. Than from the Drop down select "People who like this page"
(Follow the screenshot)

Hope this will help!

You can also learn How to Merge Facebook Duplicate Fan Pages