The problem is likely that the original comment contained both a carriage return and a line break, and when you go to put the comment back in the textarea, both are interpreted as line breaks in your browser.

Just remove all carriage returns from the text before submitting it to the database, and you should be fine.

EDIT: Something like the following, perhaps, though I imagine someone will come up with a better regex.

$text =~ s/(?:\r\n|\n\r)/\n/g;
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