> They could be using something that multiplexes or switches PCI-E lanes

Of course, they could be using a PCIe bridge to multiplex 2 input lanes to 4 output lanes, but I don't think anything could be won by multiplexing or switching lanes that all go to the very same slot anyway. They could as well multiplex 2 input lanes to 16 output lanes and claim a fully connected x16 slot ;-)

> Didn't we have a screenshot of that board at one time?

A screenshot of a board? :-) There's a shot in the A-Eon press release linked to in my comment you quoted the link to above, but it doesn't help me to identify the solution to this mystery. A block diagram would come in handy.