If website has two or more languages then Views with Menu Children Filter enabled shows menu items that have multiple translations twice.
Filter content by active site language doesn't work with Menu Children Filter.
Fix Menu Children Filter module to respect the active site language filter.
Check "Distinct" in the Query Settings under the "Other" section.
Note that this solution slows queries down.
Needs work
3.0
Code
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It's likely this issue predates Contrib.social: some issue and comment data are missing.
+1 for a patch if possible. Using Distinct should not be necessary, esp. when the view already has the "Content: Translation language (= Interface text language selected for page)" filter set.
FYI: I won't have the time to implement something here in the next month, but I'm happy to review a final MR that has been approved by the community.