I know the IRS does NOT like to have 2 returns for the same individual in one season. Did that once and got a peaceful nasty letter stating not to do that ... to amend any return roughly atleast 2 weeks after the original one..  An amendment is just what it sounds like .. correcting or adding to an original..  and YES if need by you can amend an amendment with a new one.    Just remember, must give time inbetween so they have been put in the system and processed before amending.