Hi, Izzat Hannah,
ChatGPT: I saw the movie already, so I don't want to watch it again.
I wonder if it should be (I have seen the movie already, so I don't want to watch it again).
'Already', as time adjunct, can be used with either the present perfect or the past simple, depending on the speaker’s/writer’s perspective. (See Cambridge Grammar of English). Here, the speaker is thinking of a definite point in the past when saw that movie.
From 'Practical English Usage 3rd edition, page 558:
"Various tenses are possible with all three words. In British English, perfect
tenses are common with already and yet; Americans often prefer past tenses."
|- Have you called the garage yet? (HrE)|
Did you call the garage yet? (AmE)
|- She's already left. (BrE)|
She already left. (ArnE)