This is a scan of a very old Kodachrome slide. The shot was taken with a Cokin Doble Exposure Mask, which split the image vertically. Each side was separately exposed. The metering was done in advance and the same manual exposure was set for each side.
The trick is to line up the image convincingly where they meet. This one was more successful than most.
Howard, thanks for commenting on my egg project picture, I see you put a lot of ?real? film effort into this picture. That cokin mask must have set you back some coin, neat effect, you asked about the ?flood? filter, it?s an adobe plugin written by flaming pear, they have a 30 day free trial on their website.