Imovie is saving video in two files.

The long extension file is a temporary file created to hold information temporarily while your shared movie file is being created. When you place compressed video clips into iMovie, iMovie unpacks it so that editing can take place. When you share it out iMovie re-compresses it to an .Mp4 or .mov file, depending on what settings you chose. This is called rendering. iMovie stores in the temporary file the information it needs to render. The temporary file should disappear on its own quickly after the movie has been rendered and successfully shared, as there is no longer any need for it.

-- Rich

Yes, I can see how exporting double files could be frustrating.

Here's a couple of things you can try:

1. Open iMovie while holding down the Option and Command keys and selecting to delete preferences in the box that appears. iMovie will open in a new library. Reopen your old library to get back to your project. Now see if it shares out properly.
2. If the above doesn't solve it, try doing an Edit/Select All, Edit/Copy, of the media in your project and then Edit/Paste the media into a newly created project. See if that does it.

-- Rich

You are welcome. :)

An hour is pretty long for the temporary file to disappear. However, you may have had a complex movie.

-- Rich

Actually, that's normal. The file with the long extension will disappear once the sharing is completed.

-- Rich