Facebook has deprecated the share button and replaced it with the Like button.
According to Facebook.
We deprecated the Share Button when we launched the Like button, because the Like button improves clickthrough rates by allowing users to connect with one click, and by allowing them to see which of their friends have already connected. For reference, the Share button documentation is still available here.
The plugin doesn't actually direct the share buttons which page to share, instead all of the share buttons share whatever page they are currently on. I don't think it's a bug we can fix because it's a bug in their code.
The Facebook share button may be deprecated but the Facebook like button still works well.