"one row per format" export appears to produce duplicate lines in export if identification columns are not present

[sparkhi]

If we export "one row per format", the only columns that may differ are the 4 identification columns. (PUID, MIME, FORMAT, VERSION) If these columns are not selected as part of the export, it looks as if the rows are just being duplicated.

Perhaps, in such case, consolidate it to write the row only once.