You’re confusing different numbers. To properly understand all these ID’s and numbers, please read this explanation by a fellow forum user: Demystifing Numbers (Indiegogo, Backerkit etc.)?
The Backerkit ID numbers are used in the lists of projectors that are shipped. Those are the ones IvoG said are not sequential. This is however not a problem, since these numbers aren’t used to determine shipping order. The projectors are shipped roughly by Indiegogo contribution number (ie. backer number). I say roughly because there are other factors as well, like grouping of reasonably sized shipments to different regions.