Call Control Senses the Same Incoming Number at Times Prefixed With a 1- and Other Times Not.

I currently am having to register two versions of some incoming caller numbers in my (limited) accepted list because call control will sometimes register them calling in as 1-NNN-NNN-NNNN and other times calling in as just NNN-NNN-NNNN (where NNN-NNN-NNNN is a match otherwise).

Can anything be done about this (other than me paying for an extended accepted list)?