Question about pips

So ive got pathfinder elite, and i have no idea how pips basically work, so for example if ihave one green pip on dvm (+3) can i make second one +3dvm too? Or just 1 pip of the same rarity can be dvm at a time? If yes, how do i have 8dvm starboots, and what is godroll dvm for pathfinder elite? (Not including enchants and innate stats)