wbmw, that could be. But if YB is thinking that, I find it unlikely. It would be a very cynical ploy to make a dual A64 PC that would be so compromised. The user would feel very ripped off when he sees that his PC hardly runs faster than a single A64, and it would not be a cheap machine since it is a very specialized design.
Generally, I am negative on the concept of a dual CPU consumer machine because the consumer is better advised to buy a single CPU machine and upgrade the processor after a while. However, if you have to seriously compromise the design in order to make a dual processor machine then it becomes a travesty.
Now, a dual CPU Opteron workstation - which is designed for scaling - that is a whole different thing. Anyone who has a real need for dual CPU performance had better make sure the system design can feed those hungry processors!