Sub, basically got the point regarding the PVR150's IR blaster correct. Hauppauge in a reply from there support team said that the driver for the pvr 150 has no way of handeling an individual pvr150s ir blaster or ir receiver. It simply looks for the very first card with an ir blaster/ir receiver and chooses that one (the very first one is also not gaurenteed to be in any specific order).
I've got three of these pvr150s running in my system right now. So I now it can be done. If your running anything except for the very latest release 94.13 then I suggest that you upgrade.
To handle the ir receiver problem I would suggest that the you remove the ir receiver/ir blaster from the bottom pvr 150. Only plug in one since the driver can only handle one and then you know which one will be choosen. The cards are going to be numbered starting from top to bottom, so capture device one will be in your first PCI slot and then number in increasing order from there.