Duplication

Item duplication, or "duping" as it is referred to by players, is an action which allows players to make copies of their items. Duping has resulted in an overall deflation of every limited item's value.

Axes:
Axes have most likely been the most duped item in the entire game as they have been easily duped en masse using variety of different methods.

Non Place-able Items:
Non Place-able items include things like milled wood, pumpkins, and gifts. These items have suffered less deflation in value than other items as it is liberally estimated that only around 20 players know of method in which they are duplicated and have the resources to perform the duplication.

Place-able Items:
Place-able items have been duped (prior to recent patches) using a method which involved one player placing an item on another users base-plate as they save their base.

Consequences of Duplicating Items
Defaultio usually notices users who duplicate in game commodities on a large enough scale and contacts them via a ban and a short message upon entering the game.