The two batteries has the sam capacity, but does not hold the same voltage under load.
Energy is a combination of voltage and current and the battery with the lowest voltage will have less energy.
The battery with the lowest voltage will have the highest current draw, to keep the power constant.
The battery with the lowest voltage also has the lowest trip current.
The battery has less capacity than stated on the cell, but they both have the same capacity, i.e. they can be used in series at lower loads. The difference in voltage under load shows that there must be some variation in the cells used. The cell does not work well with a 5 ampere load.
Compared to the2011 test of this cell, the capacity has been reduced.
For a cheap battery it is acceptable.
The ones from DD are also sold out. I just received my last replacement cells shipment of 6 protected cells from DD. They test to just somewhat shy of 2300mAh @ 1A and 2.826V (as measured by my UT-58E DMM)
It is not a big problem finding other batteries with about 2000mAh at the same price, there are lots of different names in cheap batteries and my guess (without testing) is that many of them will be between 2000 and 2400 mAh.