I wonder if extra grammatically correct as and are both adjectives which should not go together in one sentence?

You're right to be questioning this! "Extra" and "grammatically correct" don't work well together in this way. Here's why:

* "Extra" is an adjective, meaning it describes a noun. It typically indicates something excessive or additional.

* "Grammatically correct" is an adjective phrase, acting as a single unit describing a noun. It indicates that something adheres to grammatical rules.

The issue is that "extra" modifies the noun "grammatically correct", implying there's a way to be "more grammatically correct" than just being grammatically correct. This is illogical.

Here are some ways to revise the sentence:

* Focus on the noun: "The writing is grammatically correct." (Simple and clear)

* Clarify the meaning: "The writing is exceptionally grammatically correct." (Emphasis on the high level of correctness)

* Use a different word: "The writing is perfectly grammatically correct." (More precise)

The best way to phrase your sentence will depend on the specific context and the emphasis you want to convey.