Well, the list was given to me by players, (I think Jaros and Hayato contributed most), so I'm not even sure if it is accurate or complete, it would be exceedingly tedious to check all quests.
Anyone can collect extra spares of a one-time item, if they take the trouble of creating a new char and levelling it up untill it is strong enough to finish the quest. Since their old char has the flag, they'll be able to use it.
This is why we weren't particularly eager to remove the one-time quests - after all, they probably were made one-time for a reason by the Builder. But since we decided to give in to the whining, and since it is possible to get multiple items in other ways, so...
Yes, you have a go, to all of them, Hayato.