Reduce to Basic Appearance and Add New Fill matched the Appearance
panel's active row only when every selected object had an equal row.
With three objects whose third had a different lower fill, the second
object lost the match too: Reduce kept its top fill instead of the
active one, and Add New Fill put the copy on top instead of above the
active row.
items_per_target now matches each object against the first one
separately, so an object keeps the match whenever it has an equal row.