There isn't a specific noun form that directly corresponds to the adjective "redundant." However, you might use related nouns like:
* Redundancy: This refers to the state of being redundant, or the repetition of something unnecessary.
* Duplication: This emphasizes the repetition of something that is already present.
* Repetition: This is a general term for the act of doing something again, which can be redundant in some contexts.
The best choice will depend on the specific context and the nuance you wish to convey.