It is really interesting question.
I have observed that pashtuns always take serious their race and language.
And non pashtu speaking pashtuns often becomes the victim of mockery by those who speak their language well. Good or bad its true.
Regarding your question. I have found that their is no any tribe like mughal pathan (sorry to hurt your feelings).
Those mughals who live in pashtun countries are treated as pashtuns by outside people like punjabis, sindhi's etc. But Pashtun tribes do not recognize them as pashtun even though they speak pashto fluently.
I have some relatives who call themselves mughal pathan but they face same dilemma.