The examples in your link Garabaldi, are definitely a different shape and I notice also, the 'stripes' of your badge are progressively thinner/thicker.
As an old Army brat, I don't recall my Father wearing collar badges as a Sergeant in the NZ Army; and here's my maternal Grandfather, Colour Sergeant, Royal Artillery (British) WW1
I don't recall anything like that (insignia) from the Army being marked "GI." I may be wrong but I think is is a hallmark from something else, maybe even costume jewelry. Possibly even GI Joe related.
I should have added we bought our chevrons at the Army Navy Surplus store. They were larger than the civilian ones and looked better on the collar, plus they were solid brass and could be polished and lacquered. The civilian models were plated. They also sold the smaller ones for what were then called WAFS for the women officer's uniforms. Monty