Imagine the following circuit with two capacitors and diodes acting as passive PFC.

My question is what is the capacity of these two capacitors? I mean compared to a circuit with just a single capacitor. Some people say they are in series so their capacity is halved, but I am unable to understand it.

As an example: Let's have 230 VAC, so we want to get approximately 316 VDC from AC-DC converter. We could use a single 400 V capacitor, let's say we take 10 uF. Without PFC. Now, if we use two capacitors instead, 200 V and 10 uF each, and connect them to this PFC circuit, the result will be just like having a single 5 uF capcitor? If this is truth I must be missing something, because I expect the capacitors are charged to 10 uF each and then discharged in parallel, so their capacity is actually added and only voltage is halved.

The reason why I ask this question here is that I read a review of one ATX power supply and the reviewer wrote that it contains a pair of input filtering capacitors in series, so their capacity is halved and it is insufficient. But as it was a passive PFC power supply, I expect this valley fill filter to be used there and I'd like to know whether the statement on halving the capacity is then correct.