Summary of Configuration: Fedora 23 (64 bit), fresh install (not an upgrade from 22), fully patched. Two Google Apps calendars via GOA and one WebDav calendar configured directly via Evolution. Description of problem: If I copy and event (right click->copy) and then paste it into say the following day (right click->paste) the calendar the event was associated with is not preserved and the event is always pasted into the default calendar as configured in Evolution. I can always reproduce the behaviour in my environment.
Thanks for a bug report. There's a problem with this. The Ctrl+C/Ctrl+V stroke doesn't know what the user wants. Users sometimes prefer to paste to the same calendar, the same as you, but other prefer to paste to the selected calendar (in the left tree), While the behaviour can be easily changed by selecting a different calendar in the list of calendars, it's not that simple to paste to a different calendar when it would default to always paste to the same calendar as the source calendar.