A Wittgensteinian dismissal of a "deep" question:
The statement is meaningless because there is no
criterion of similarity between sensations.
It is just like saying "Is my promise to love, honor and obey the same as her promise to love, honor and obey?". The question cannot be understood because it appeals to a rule that does not exist: the rule that would state the conditions for two promises to be `the same'. There is no such rule and hence there is no such question.
Both cases rest on the same misapprehension: the idea that abstract nouns like `sensation' and `promise' can be used just like any concrete noun. In both cases there is a concrete object/action nearby to confuse us: the thing that is sensed/promised. One can indeed ask whether the red object I see is the same as the red object you see. One can also ask whether I promised to do the same thing as she did. For concrete things there do exist criteria of similarity: there are rules that state when two objects or actions are the same. This is not so for the abstract sensation/promise itself. No amount of research could `uncover the truth' as to the similarity of different peoples' sensations. In the absence of a criterion of similarity there is no such truth.
[For a whole book based on this point, check out Daniel Dennett's "Consciousness Explained" ]