His may have two clips- but on w126's Bosch units there is a space specially made for a clip on both sides of the top and bottom, and a special space made for a clip in the center of the top and bottom, as well as one space on either side.
This turns out to the number I stated. After finding over a two dozen Bosch units in the yards here, they all conform to this. You can have less clips installed than this number, but why?
BTW, there is usually no problems in removing the glass lens completely- I've never had the gasket tear or "go bad" from removing it. Indeed, if the gasket is bad, you'd be better off getting it out and replacing it, or doing your best to get it functioning properly- the gasket cost peanuts compared to the damage a bad gasket can do. Don't forget to grease the two gaskets on the doors for the lamp access while you're at it.