I draw your attention to the tags like and facebook-like.

Only like has a tag wiki, which currently reads:

A way to give positive feedback or to connect with things you care about on Facebook.

So, they're obviously synonyms of each other.

like by itself is awfully generic. I suspect that it was created when someone tagged their question facebook like instead of facebook-like. (An easy mistake to make.)

I don't have a particular suggestion as to how this should be handled except that it should be handled.