Every weld bead deposited experiences a thermal cycle with a temperature increase to the melting temperature and then back down to the interpass temperature, which in the case of carbon steel or high strength low alloy steel would be well below the lower temperature of transformation. In the case of a multipass weld. the weld bead being deposited as well as the adjacent weld beads can also experience temperature excursions above the lower temperature of transformation and then cool to a temperature below the lower temperature of transformation.
In the case of pipe joints, it would not be typical for a welded joint to be completed using a single bead for all but thin walled pipe or tubing. So, the weld is going to undergo several thermal cycles. It would be no different for two separate welds, side by side, as it would be for a multiple pass weld. The thermal cycling would be very similar. The microstructure would also be very similar if the same preheat and interpass temperatures are similar.
Best regards - Al