No disagreement about relevance of baseball caps for organ transplantations, but if TDT is defined using "all other instantiations and simulations of that computation", any small difference, however irrelevant, may exclude the agent from the category of instantiations of the same computation. The obvious countermeasure would be to ask TDT to include outputs not only of other instantiations of itself, but of a broader class of agents which behave similarly in all relevant aspects (in given situation). Which leads to the question how to precisely define "relevant", which, as far as I understand, is the parent comment asking.