Cleared up by Mak. Dan is writing a new iCarly while filming Victorious
"But here's his tweet "JUST settled into my iCarly office! Now... making @iCarly and @Victorious at the SAME TIME. Let the games begin!!! :)"
Nathan's reply made me LOL
And lastly Jennette's reply to Nathan's reply to Dan.
@NathanKress @DanWarp i second that.