I was looking through Dan's videos Here I found something http://www.youtube.com/watch?v=PVEOJW2StSs&context=C3f5df75ADOEgsToPDskLi9cmcZ_yED2q6jgn6VLw7
In the user Comment section, he put this
(for what ever reson Dan removed this comment.)
Hey guys! Dan Schneider (@DanWarp) here. This video of me scaring Miranda and Jennette was shot TODAY (February 13, 2012) in iCarly season 5. We were RE-CREATING the scene from a season 1 episode called iHatch Chicks. In this new video, Carly and Sam look younger because we did their hair and clothing to make them look like they did 4 or 5 years ago, when we shot the original iHatch Chicks episode. Thumbs up! :)
So at this point I don't really know maybe we rally are in season 5.
My opio is that season 2 was not split or Nick just combined production season 3 and 4.
I am still trying to look into this though.