So whenever questions of precedence and priority erupt among my creative friends, somebody is liable to say “If this is anybody but [actual originator], [purported originator] is stealing [intermediary]’s bit!” or some variation.

“If this is anybody but J.R.R. Tolkien, J.K. Rowling is stealing Susan Cooper’s bit!”

They’re all nice ways of saying “ignorant blather,” anyway….

Edward Tufte points out strange use of the word “influences” to describe the relationship between an artist/work and an earlier artist/work. As though the agency existed within the person in the past, and the later person was merely the passive recipient of the predecessor’s intentions. It does seem to imply that an artist draws on earlier works, consciously or unconsciously.

I don’t have a fancy name for it, but I’ve experienced it many times. For example, thinking Unamuno’s Niebla was a cliché because I’d read many books written after Niebla that did the same thing.

Maybe “narcissistic anachronism”?

I think the phrase/word you’re looking for may be:

accidental coincidence / homoplasy – A reading whose similarity with a corresponding reading in another text is not due to common descent.

http://www.mindspring.com/~scarlson/tc/glossary.htm

If you want a neologism, some combination of Chronological and Confusion might work: “Chronofusion” perhaps?