Same film?

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How can I merge two titles?

Before I merge them, I would like someone else to verify that they are the same title.

Using Collaboration search (on the Advanced Search menu), they have 7 names in common:
https://www.imdb.com/search/name/?roles=tt0071865,tt0163111

Then editing the URL to "not" (symbol !) to each in turn, find these differences:
Credited in Mozart: A Childhood Chronicle (1976), Not Mozart - Aufzeichnungen einer Jugend (1976) (Sorted by Popularity Ascending) (3 actors and a self)
Credited in Mozart - Aufzeichnungen einer Jugend (1976), Not Mozart: A Childhood Chronicle (1976) (Sorted by Popularity Ascending) 0 results
I'll leave it to you to analyze whether these are additional credits, or alternate credits for the same characters (perhaps English voiceover?)

Comparing the runtimes and the release dates pages, it looks promising, but you should do some google searches on the titles. Maybe you'll find some press releases, or a Wikipedia entry. Just build a document of where you've been and what you found there (an annotated webliography) so that you can eventually paste it here and cite this page as your reason for merging in the Contribution submission.