Those turn signals are from a 9-5 not a 9-3 lol.
That is normal. Only one bulb is supposed to flash when signaling the other one is for the backup (reverse) lights. What probably happend was that one of the lamps was removed for some reason and the 2 bulbs were installed in the wrong places. Simple and that means is that you don't have a problem

The back bulb is the one that is for the blinker and the front one is for the reverse lights
