a. It is a common resource to oppose a new Perfect to the old one, generally with zero-grade of the Perfect stem and middle endings, so that the first becomes only Active and the second Middle. This is a general resource in Southern Dialects, but not in the European ones.
NOTE. We use it in our system, though, to distinguish the different Perfect forms more easily.
b. The Past Perfect or Pluperfect was also created to oppose it to the old Perfect, so that it became Present Perfect. It is formed with secondary endings added to the Perfect Stem.