Dad bought one like the one in the bottom 2 pix probably 25 years ago. It was Hesston branded but the patent rights went back to a Dutch company. It was referred to as a tedder rake. It did a good but not great job of raking sickle mowed prairie hay, but where it really shined, and was developed for, was to rake alfalfa that had been rained on and was already in a windrow. The rake would move the windrow over onto dry ground and the fingers or teeth on the rake would open up the windrow, fluffing it, if you will, to let air get to the hay and decrease drying time so you could bale sooner.
As far as putting 2 windrows together that had been swathed with a 16 foot header, fugeddaboutit.....ain't gonna happen. You'd do better with an old New Holland side delivery rake (a model 56?)