I can offer a theory, which is only speculation.
Since episodes weren't satellite fed in those days (that we know of), the episodes were aired in order but had different air dates in each city. Case in point: WIVB Buffalo started airing new Joker's Wild episodes in late August 1977. WROC Rochester started a couple of weeks after that, and CITY Toronto a couple of weeks after that. Each started with the premiere. Maybe they only had a set number of tapes but because of different debut dates in nearby cities, those stations may have just shared the same tapes.
In the show's second season, WIVB dropped it and WKBW picked it up, but didn't start showing it until mid-season. They started with the second-season premiere.