2 full bit PCI Express slots?

That would be x16, PCIe is rated in the number of data paths. The most I've heard of any chipset potentially supporting is 32 data paths, that would be 2 x16 slots and no other slots! That's why companies are planning boards with 2 x16 slots operating in x8 mode, with 1/2 the throughput.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

PCIe x8=2000MB/s. AGP8x=2048MB/s

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>

Dual AGP has only been possible since AGP 3.0 spec and likely requires special hardware to negotiate trasactions. Most companies were already beginning preparations for PCIe when AGP 3.0 was introduced, so they passed up the opportunity. Alienware had a special dual AGP board designed specifically for them, but you probably won't be able to buy it separately.

<font color=blue>Only a place as big as the internet could be home to a hero as big as Crashman!</font color=blue>
<font color=red>Only a place as big as the internet could be home to an ego as large as Crashman's!</font color=red>