I don't know which Asus board you ordered but looking at the spec for what you got seems fine, supports crossfire and AMD Phenom series CPU's.
Most Asus boards have this arrangement,
1 x PCIe 2.0 x16 (blue)
1 x PCIe 2.0 x16 (x4 mode, black)
To support the same as Gigabyte does. Personally I prefer Asus, but I don't the supplier is at odds for sending you a very nearly exact part from a different manufacturer.