Then we have a contradiction.
If blue chests are getting duped, then obviously bus can be duped. This would cause insane amounts of incomeing gold. Prices go up. Prices are going down though, so blue chests cannot be being duped.
Now, that being said, Items are being duped and sold for cash (only source of income for the dupe method) at cheap prices so they can use the cash to buy legit items off the market, thus money laundering. This would be the cause of sudden bursts of really cheap items on the market.
So whats REALLY going on here?