Parallelomania
One biblical scholar's 1961 lecture named and defined this error precisely, arguing that surface resemblance alone proves nothing about actual historical connection. It is, in effect, the standard by which any claim of cross-tradition influence or borrowing ought to be judged — including many of the comparative claims found throughout esoteric and comparative-religion writing.
Samuel Sandmel, 'Parallelomania', Journal of Biblical Literature (1962)
A named scholarly term for the specific error of treating any similarity between two traditions as proof that one descended from or influenced the other.