Rename "copy" to "duplicate" for the "copy schedule" feature

[charlieweinberger]

Currently, a user can click a button (image 1) and, as the website currently says, "copy [their] schedule". However, I think this feature is better described as the user duplicating their schedule. The word "copy" is ambiguous in this context - it could mean copy-pasting the schedule into another schedule, for example. The word "duplicate" is more accurate in describing what will happen next. All instances of the word "copy" (ex: image 2) should be replaced with the word "duplicate".