This thread is resolved. Here is a description of the problem and solution.
Problem: Duplicate icon is missing in page editor
Solution: On Page Editor -> Multilingual content setup if you have chosen "Make 'Pages' appear as translated" the duplicate button will be hidden.
This is a normal behavior as pages without translations are automatically marked as duplicate using this feature if you want the duplicate feature anyway, you can choose "Make pages translatable" and duplicate it.
This is the technical support forum for WPML - the multilingual WordPress plugin.
Everyone can read, but only WPML clients can post here. WPML team is replying on the forum 6 days per week, 22 hours per day.