Last 256 I had had a piece of oil well drill stem inside another so it could be slid out in the field to pick up the tongue of the second rake. It was just welded onto the back of the frame of the rake.
With 2 in the same direction, it would be for short grass. For my long stemmed sudan I need the Vee function as 3 windrows are max for combining; usually only 2 and I can go back and forth quickly. So I have a dolly with 2 wheels and sliding rails to set different rake spacing, depending on the windrow width desired. One of my rakes is LH and the other RH. They run side by side rather in tandem.
It offers no advantage on the short grass where I have to bring 4 or more rows together; nor where the field is small and adjacent obstacles plentiful.
For that I just use one and make lots of trips. Your double discharge on the same side would be ideal.
Other thing is my old rake was 7' and the new ones 9'. Makes a whopping difference when you are raking behind a 9' swather.