Unnecessary repetition can be a frustrating experience and can lead to confusion when trying to communicate effectively. To avoid this, it's important to have a range of synonyms to replace the phrase "unnecessary repetition". Some suitable alternatives include redundancy, reiteration, duplication, and superfluity. Redundancy refers to the act of repeating something that has already been said. Reiteration, on the other hand, entails the act of saying something again, usually for emphasis. Duplication refers to the occurrence of the same thing or information in two or more places. Finally, superfluity refers to the presence of something that is not needed or necessary. All these synonyms provide a range of options to use when trying to avoid unnecessary repetition in language.