The logo on Norma ammo primers

Some Norma rifle ammo has primers marked “NP” and other Norma ammo does not. Are both types potentially original, or should all older Norma ammo have marked primers?

And I notice two colors of primer metal on older Norma ammo. Same question?

By older I mean decades old, at least 30 years or so. I shoot older ammo almost exclusively.

If i remember correctly the NP marking stopped sometime in the early 1960’s.