I have two power strips connected in serial. It is wall-strip A-strip B.

I have two Huawei cell phones, different models. When I plug phone A to
strip B, the phone can charge. However, if I plug phone B to strip B,
after overnight, the battery capacity is still zero (zero to start with).

If I plug phone A or B to strip A, it can charge.

In conclusion:

strip B can charge only phone A but not phone B.
strip A can charge both phones.

Any explanation to this mystery? Thanks.