That's actually the first time I've seen it. many moons ago while I was still able to work in construction trades, My boss had us putting in a vinyl IG at his house. He opted for the clip-in lining, and the auto cover. We had to locate the winter tie-downs within 1" of optimal. First winter heavy snow and ice tore the cover. What a mess!
I've since helped with other IG vinyls, and have never seen liner and cover in the same track. Personally, I don't think it's a good idea. Present thread as an example.