When two parkings are close, it's possible one jetway or the other will activate depending both by which airplane you use and how far from the stop position you park.
Sometimes it's usually possible to fix this by playing with the parking radius in the AFCAD, but of course this has side effects too because, making it smaller so parkings not overlap, might cause the jetway to just stop working because it might end up outside of the parking, and making it bigger might cause overlapping of radiuses, so FSX will be confused which jetway to activate, and in addition to that, playing with the radius might affect AI airplanes too...
We'll have a look at the AFACD to check if it's possible to fix this.