On a csv import comments are being twice.

[Daniel Santos]

Another guess is that you are updating an existing issue. When an issue is updated the old comments are not removed, but the new ones are added. There is no validation to check if a comment already exist. If a comment is already there and you import it again from the CSV, it will be duplicated.

[Nic Brough -Adaptavist-]

There's not really enough information here, or a full question.  When importing from CSV, there's something about comments is clear, but "are being twice" doesn't tell us much.

My best guess is that you're saying that you have put a comment in your CSV, and are seeing it imported as two comments instead of one.

You'll need to explain which CSV import you're using, give us a view of your plain CSV and most importantly, how you have done the field-column mappings.