In one of the cummentaries they said, "that's one of the rare times Spenny was on the left side of the couch"
In total, Spenny was on the left side 37 times. All 26 episodes of season 1 were with Spenny on the left, then it began to switch a few here and there throughout Season 2. From Season 3 onward, Spenny was on the right, minus the Arm Wrestling episode where the paper he left was on the left side.
The Pilot didn't have a couch starting scene. In Earn The Most Moneyepisode, Kenny was sleeping, so technically Kenny was on the right side as it was empty, but if you don't count it, as unlike the Arm Wrestling episode where Spenny left something on the couch, Kenny left nothing on the couch. So if we remove it, Kenny was on the left 49 times and Spenny 37 times, 36 times if you remove the Arm Wrestling episode.