For privacy reasons the ip-addresses should not be included in thread reports (at least optional): The threads are not dynamic and may never be deleted, but the user accounts may be deleted.
Oh, sorry, did not look at the code of the multi account report postings. You use a special bb code. I thought the report including ip address was saved as text to the post table.
Then that's fine, as long as these reports are (optionally) deleted once a user account gets deleted. the personal data (including ip address) of a user has to be deleted on user deletion (at least in the EU).