You can do this by going to 'Resources' on the right hand side of your Page when you go into the Edit section. Here you'll see the option to merge Pages that have an identical brand name to yours :
If you have other community Pages that have the identical name to you, you'll see this option, otherwise Facebook will notify you that you have no current Pages to merge with. This is not an automatic process, but it will notify the Facebook team, where it will take up to 7 days for the request to complete. Once this is done, the fans of that Page will automatically be on yours. When you see the new fans join, you might want to leave a post to welcome them to the Page and explain why they're now seeing your wall updates, as they won't receive a notification to let them know the Page has changed