We see the same thing with combo here (Norcal). Players self-rate for the fall combo season and dominate. Since combo doesn't count towards ratings, they dominate again in the adult league the following spring. They then get a second round of domination at combo since it take place before the new ratings are published.
I'd really like to see all USTA matches used in the NTRP calculations (except maybe mixed since it has a different dynamic) to limit the ability of captains (I blame them more than the players) to bring in ringers and use them for multiple years.