When Donnie's parents are talking about Frankie Feedler are they referring to Frank's father? Based on Frank saying that his father and grandfather were called Frank also.

from Movie FAQ – Donnie Darko on Rap Genius

Meaning

It’s possible, although it seems a bit unlikely, since it would require Frank to be the offspring of a very young father.

Of course, no one other than Richard Kelly knows for sure, and this detail has never been covered. It seems likely as, in the notes of The Philosophy of Time Travel, Frank’s surname is revealed to be Anderson.

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