Dual fan variants: advantages and disadvantages

What are actually the advantages of the decentralized devices with 2 smaller fans in one duct compared to the classic versions with 1 larger fan? Somehow I can't find anything concrete about this. Are these used in special situations?

Doesn't anyone here have an idea? Has anyone installed these dual fans? If yes, why?

Aren't they for heat recovery? Old warm air out and new cold air in. In the heat exchanger, part of the energy is then recovered. A fan can only ventilate or, by reversing polarity, push the air back and forth.

Doesn't anyone have an idea here? Has anyone installed these dual fans? If yes, why?

Who manufactures something like this? I've never heard of it - until now it's always been "pipe in the wall, on the inside a reversible fan". How are the motors/fans installed? If the "exhaust motor with fan" is installed in the pipe, it is actually in the way of the "supply motor with fan" and costs efficiency (not to mention the additional costs due to double the material).

Maybe a large case with two fans in two pipes, each with dedicated ventilation directions, but with a heat exchanger that can operate in both channels?

There are also decentralized ventilation systems with counterflow heat exchangers - however, I have never seen them in practice, but I would always prefer them over the swing fans.

Just google Passive House Institute and then look at the component database. There are a few decentralized ventilation units for single rooms listed there.