This thread is resolved. Here is a description of the problem and solution.
Problem: I can't duplicate a page if the role of the user is set to "editor"
Solution: This used to be a WPML restriction which was fixed in WPML 22.214.171.124
This is the technical support forum for WPML - the multilingual WordPress plugin.
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This topic is split from https://wpml.org/forums/topic/duplicate-post-isnt-working-for-editors/