Learn more about Grammar:
Adjectives: An Easy Guide with ExamplesAdverbial Clauses: What Are They?AdverbsAnalogy: Definition & Meaning (with Examples)ArticlesBad AdverbsClauses: Definition, Meaning, and How to Use ThemConjunctionsCoordinating Conjunctions: What Are They and When Should You Use Them?Dangling ModifiersDeclarative Sentence: Examples + MeaningExaggerationHomophones: Definition and ExamplesHow to Use Subordinating ConjunctionsInfinitivesInterjections: Definition, Meaning, and ExamplesIntransitive Verb: Definition, Meaning, and ExamplesNounsParticiples PluralsPrepositional Phrase: What Is It & How to UsePrepositionsSplit Infinitive: The Complete Guide (with Examples)Subordinate Clause: Definition, Types, and ExamplesThe Complete Guide to Transitive VerbsTransitions: A Complete Guide (with 100+ Examples)Types of VerbsVerbsWhat is a Pronoun? Rules and ExamplesWhat Is Symbolism in Writing?Word ClassesRepeated Synonyms

Every word in your writing should have a purpose. If you have sentences with redundant expressions, the sentences will be overly long for no reason. Look at these examples:
- An inefficient, faulty task is set.
- Boring, tedious tasks are not fun.
- This is an annoying and irritating task.
In all three sentences, there are redundant adjectives. The second adjective doesn't add more information, so remove it from your writing.
A synonym is a word that means nearly the same thing as another word. For instance, "boring" and "tedious" are synonyms, as both mean something close to "not interesting."
Using two synonyms in the same phrase makes your writing repetitive. Instead of saying the same thing twice, replace the second adjective with one that gives additional information. Look at the following example:
Repetitive sentence: Boring, tedious tasks are not fun. Engaging sentence: Boring, time-consuming tasks are not fun.
The first sentence uses two words that mean the same thing twice. In the second sentence, the second adjective, "time-consuming", gives more information about the tasks. Including that adjective adds value and meaning to the sentence.
If you can't figure out an adjective to replace your redundant synonym, then it's fine to remove that synonym from your sentence. Better to be brief than wordy.