The answer requires an additional question. Was the parachute with the smaller hole oscillating? If the hole is too small the air flowing into the parachute will have to escape somewhere else. The lighter the weight the more it will want to release air from the skirt causing the parachute to oscillate (wobble back and forth spilling air out the edges) and momentarily accelerate towards the ground. The larger hole will stabilize the system so it is less prone to oscillation. This results in a more constant rate of descent. Of course if the large hole is too large the parachute will descend much too fast.