"Enemies drop an additional item with every timed loot drop."
The actual code, causes a 100% increase in chance to drop loot, which can result in double drops. This does not make every drop a double, like the text might indicate.
This ability can pay for itself very quickly. Your initial supply will start very low, and having lots of extra gear to sell at the black market, can make all the difference in an improved start. Legendary players will recommend getting it as soon as possible.