Another Turn Signal Issue
 

What causes both the inside direction signals to flash at the same time while the exterior signals are operating just fine ??

Incorrect or ill matched bulbs in the 4 corners will do this as will bulbs that are lower wattage than spec. I ditched my Narva bulbs for Hella bulbs and the double flashing inside went away. Funny thing was the first flash was always good, the correct warning bulb in the instrument panel flashed nice and bright, then both bulbs would flash together but less brightly.

Worn out indicator relay could cause the same symptoms. Try to fit a new one, and see if all lights up as it should.