O, that this too too grammar error would melt… I’m sure that Shakespeare wouldn’t mind my re-writing one of his most famous and quoted lines—as long as it’s done in the name of good grammar. Most people don’t have problems remembering that two refers to the number 2, just as twins (notice the tw) refers to two (notice the tw) of something. The problem usually comes in trying to determine whether to use to or too.
To is a preposition, as in We’re going to the opera and They drove to the lawyer’s office. Too generally means also, as in You can’t have your cake and eat it, too, or it can refer to something done in excess of what is normal or desirable, as in The soprano was too loud.
Sherry
Everything Language and Grammar 