In a print manuscript, or in a Word DOC, it doesn't matter a damn whether you use one space or two. Or ten. The whole issue is a ghost.
Really, no one in the real world of publishing cares a damn whether you use one space, two spaces, or ten spaces after a sentence. This is a holdover from years ago when some electronic files wouldn't convert properly with two spaces after a sentence. It was never meant to apply to print, and today there's no reason to apply it anywhere.
As an editor, two spaces still provide the same function they always did, which is to make reading a little easier, and to provide a bit more room for inserting proofreaders' marks.