I've taken a real IQ test that took three hours, I did so with a psychiatrist at one of the top medical schools on the continent. This was recent, roughly ten years ago.
It was a test within a clinical setting, and I got six different scores. Some were similar and some were different. However, other people get much larger differences.
I have demonstrated that the people who work in the field believe that IQ has different subcomponents, and that people regularly score different scores on those tests.
It is also the case, separately, that your statement is ridiculous. Of our 20,000 genes (never mind the proteome and the microflora), one third are expressed primarily in the brain. That suggests several thousand independent variables at a minimum. Your belief, that intelligence is a single variable, is extremely unlikely. For that to be true, those 7,000 genes would have to always vary in unison.
But we have a researcher in neuroscience on this forum, so we can get a second opinion from an actual expert:
@Ozymandias , how many principal components are there to "intelligence"? Is it obviously true that hockey IQ and IQ are identical?