There are many different types of Gibson saddles and we dont know why the thickness is different.
Previously selling 3.15-3.18mm each manufacturer, most of the 3.3mm ones are 3.3mm.
Although a considerable number of tests is required to include the age and model, probably some previous models are 3.15 to 3.18 mm and the current model feels like 3.3 mm, but we cannot guarantee that we recommend measuring the thickness before purchasing.
Please note that we are not responsible for any damage during installation process