Ramble, Eternal Witness does not duplicate itself. It does not put a copy into the discard pile and into your deck. The copy goes into your deck instead of into your discard pile.
Additionally, if you have a level 3 Ramble in either your deck or your discard pile at the end of rank 1, it will get shuffled into your deck when you gain a rank. You will be able to draw and play the level 3 version in rank 2.
Currently, six cards can put a level 3 creature in play in Rank 1: