The original thought experiment is used to provide a pure example of quantifying and comparing arbitrary levels of suffering as a test to see whether we support such a type of utilitarian consequentialism.

By comparing torture to torture, you are changing the scenario to test a slightly weaker version of the original type of utilitarian consequentialism where you do quantify and compare arbitrary changes to absolute levels of suffering with arbitrary absolute levels of suffering but not necessarily allowing the two instances of absolute levels of suffering to be arbitrary with respect to each other.

If anyone could rewrite this comment to be comprehensible I would appreciate it.