No, every transmitter sends out the exact same transmissions on every channel...100% synchronized. What you're seeing is pretty normal, it's just the same message being decoded multiple times. The BSI transmission lasts ~20 seconds, and so DSD+ is just hiccuping a bit as it decodes the continuous message.
Also note that Motorola ASTRO 25 systems (which FIRST is) at System Release 7.16 or newer continuously broadcast the BSI over the control channel, which can be observed on some systems in the data stream. They may also broadcast the BSI in the traditional manner, which is over a traffic channel as an analog CWID, which will also appear in the data stream of the control channel as you're observing in DSD+.