On moredetail.pl there is both Last returned by and Last borrower. It would be good to change this display somewhat, after Bug 26993, to offer better clarity between the two. See this comment: https://bugs.koha-community.org/bugzilla3/show_bug.cgi?id=26993#c33
More clearly labeling what comes from the old_issues table and what comes from items_last_borrower could be helpful. If nothing else, it tends to confuse people that the bit of data labeled "Last borrower" on moredetail.pl is _not_ the data related to the StoreLastBorrower system preference. On the other hand, I can't think of why one would ever need to see both the old_issues and items_last_borrower data unless either some of the old_issues data has been anonymized or you've got items_last_borrower set to retain fewer than 3 previous borrowers (the page shows up to 3 previous borrowers from old_issues). So perhaps we could sort of coalesce this data into one display that pulls from old_issues first but if that old_issues data is anonymized checks items_last_borrower instead. It could display 3 borrowers back by default but increase that to the number of borrowers set in StoreLastBorrower if that's greater than 3. But we run into a complication because items_last_borrower only records at checkin of an item, while the old_issues data updates on checkout.