We start with something like this:
blah, blah, blah
Just add this to your list of fields:
(You don't have the "A", "B", "C" and "D" if you'd rather let all the columns be called "rowid" and count column positions--which is what I actually did.)
The output looks like gibberish, but on at least one of the columns the rowid will have at least one character different from the previous row within the same set of "identical" rows. That's the table at fault.