[MM6] Mechanics behind duplicating items from one map to next?

[Graff]

I tried googling this one a bit but haven't found anything on the subject. Certain items can be spawned from one map onto another. If you leave from New Sorpigal to Ironfist by foot, the horseshoes from the volcano spawn by the inn near Snergle's Caverns (one is under the inn... incredibly annoying.) However, if you leave for Ironfist by coach the shoes won't be there. Similarly, if on your first visit to Bootleg Bay you head directly east from the Tomb of Ethric the Mad the two herbs from that around the tomb will spawn in the same place. You have to run and quickly snag the berries because they spawn above the water and fall in.Anyways, the reason I'm posting is that I recall on my last playthrough being able to get the horseshoes to dupe from New Sorpigal to another land besides Ironfirst but now I can't remember which one or how I did it. Any thoughts?

[Tomsod]

Here's a wonderful article on the subject. Unfortunately, it's in Russian, but you can try your luck with Google Translate. The author boasts multiplying the original 14 horseshoes to as much as 92!

I can also add my personal findings to it, as I recently investigated this bug myself, albeit in MM7 (but the mechanics should be the same). The gist is: there's a list of items and other map objects (like fireballs). When you travel by coach, boat, or Town Portal, the list is erased, then refilled with the new map's items. But when you travel by foot, it isn't erased first due to a bug. Naturally, when adding the new map's items, some slots in the list will be overwritten, but those that aren't will be duplicated. The game also ostensibly keeps a total count of map items, but due to another bug it's recalculated every time a new item is added during gameplay. This is why the duplicated items sometimes only appear after you shoot an arrow (which is a map object).

Anyway, the important thing is, it's not necessary to travel to a map you never seen before for the duplication to occur! The sufficient (but not necessary; it's complicated) condition is for the new map to contain less item than the old one. Thus, if you collect all ground items from a map, traveling into it from another region will most likely duplicate that region's items. This way you can get basically unlimited horseshoes.