I got one of the 5906 from CDNN, it had the round trigger guard, I do not believe they had any square guards, at least not NIB. They do have police trade ins which may or may not have the square guard. Mine was very surely NIB in all respects. Bought that, the 410 and the 6906, could not resist the NIB price. They were all as advertised. I also have a 6904 with the square guard, kind of prefer the round guard now.
Unfortuntely my wife is a cop and knows the difference between guns, tried to tell her that I just had the 6904 refinished and the guard rounded. She just gave me the look, till I handed over the 6904, which now has replaced/supplemented her M36. Now making up for it by telling everyone that I am married to the only cop better looking than Mariska Haggerty (wife is SVU Detective). In another 6 months maybe I can buy another gun.