In recent years less importance has been given to double P1, and it's now suggested that judges do not penalise one or two double P1's, but missing teeth should be considered a serious fault.
"Premolars -Used for cutting, holding, shearing and breaking food into small pieces. Puppies do not have
P1 teeth. Adults have eight (8) premolars in the upper jaw and eight (8) in the lower jaw, four
(4) on each side. The premolars vary in size from the smallest (P1) to the largest (P4 upper)
apart from the P1 they have a serrated crown. The most common of faults is missing or additional premolar 1 in either the upper or lower
jaw, it has not been scientifically proven that these are linked hereditarily, however, there are
clear bloodline connections which link these faults. While additional P1 teeth are undesirable,
they should not be penalised in the show ring."
I firmly believe there is a family link to additional P1's as I know exactly when it started here and it has nothing to do with Lucca.