The sewn edges all the way around is an "improvement" of difference between the original carpet and what the carpet reproducer has produced sine the early 80s and possibly before that.
In 65 we can find some examples of originals with two sewn edges. Once mounted these would be the top and inner edge as shown in a 65 San Jose focused thread on the subject. If interested search for "65 San Jose Fastback Quarter Panel Trim Carpet" But the majority of the examples are of the sections with no sewn edges
Now for 66 San Jose fastbacks all of the originals I've found and seen have been from the provider with no sewn edges. I've been tracking this difference for over three decades so have likely seen hundreds. Some examples below
Challenge over the years is that carpet and one or more seats are often the first thing that get replaced early in the cars life
Hope this helps