Use the fully typed words
Don't drop the first letter off the second word just because it happens to match. Dropping the first letter of the second word implies a new one word trademark.
People usually type out the full words of things they are searching for as evidenced by this image which was captured from the DirecTV homepage...

As a window washer I would rather use one of the following URLs instead of trying to educate the entire world to only type one W...
windowwasher.com
window-washer.com
Perhaps if you are a guy named Asher who cleans Windows and all the locals know you as "Window Asher" then dropping the second W
makes sense...
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