Number of cores has increased. Only it hasn't!!

This is an odd one, to me at least. I’m rendering on a single Core 2 Extreme (dual-core) workstation yet the Vray frame buffer appears to show more than 2 cores in operation. See image attached (max file also attached).

However, when I compare render times to a different scene files with the same render settings (I matched the render settings between 2 files to check) there is no difference in render times despite the other scene’s Vray frame buffer showing only 2 cores in use. Up to now all my scenes only show 2 cores in use in the Vray frame buffer. It is only this file and I can’t seem to find what setting I changed for this to happen.

Has anybody seen something like this before?

Thanks.
DOUBLE NUMBER OF CORES.zip (28.4 KB)