I have received a decision letter on my paper from editor "I am prepared to accept this manuscript for publication provided that the authors perform some editing to improve the grammar throughout the paper" After submitting revised version, I have noticed a couple of minor corrections that need to be made with regard to writing errors after revision (One sentence was written twice and some punctuation mistakes). Should I bring these up now or just wait for the copy editing phase?
You should ask the editor who approved your paper about what to do. Resubmitting a new version might speed up their process or might make no matter. And, not all journals/conferences will have a copy editing phase in any case.
But leaving it unstated is just sloppy work and if it is recognized you might actually face rejection since the acceptance seems to have been conditional. Make your best effort.