I understand. I can be difficult to map when other data is obscuring your view. 

Thank you for thinking about how you could restore the map's existing data. Copy and pasting was a interesting idea and can be really useful when you're mapping features that have the exact same shape, though there are some draw backs to this method and better ways of achieving your objective.

You can press `w` to toggle wireframe mode. This will reduce the visibility of areas (the highlight/fill).

You can filter out data that's either in your way or you don't want to edit via the map panel on right. Press `u` to open map data, then scroll down and toggle the check boxes to select what data you want to see and be able to interact with. Warnings about hidden data will still appear.

Hope this helps. You can check out https://wiki.openstreetmap.org/wiki/ID 