I can tell just by looking at the models that they are both Sapphire models. I'm going to guess that they both have 2GBs per GPU. You should be able to CF them together just fine. Any 5970 should CF with any other 5970.
Another question is there 2 diff 100280-4gsr's a pci 2.1 and a 2.0? I don't really know what one I have how do I check that if I don't have it installed yet? I bought the sapphire 5970 100280-4gsr with the call of duty and dirt game bundle
On a PCIe 2.0 board it won't make any difference. It will drop down to PCIe 2.0 anyways. If you have an older PCIe 1.0 board you could have some compatibility issues. The 2.0 card should be bought if thats the case. Other then that, it makes no difference.