The battery expert is correct. Two en3's provide more available current at the same voltage level. Just think of it as potential.
Example: A garden hose with a funnel on top. You have two one gallon jugs of water. You pour water from one jug only into the funnel and it drains down the hose at a certain rate until the jug is empty. If you pour water out of both at the same time, the rate of flow does not increase down the hose, but it will take longer to drain both jugs.
So consider the en3 as one jug. It can provide the same rate of flow down the hose, just for a shorter duration.