Some things are just repeating 99% of the same info, but changing 1 thing.
It would be awesome to click a duplicate button on an existing item/prop/propSet to prefill all the info so we only need to swap 1 or 2 things.
This would not only help for time, but also for accuracy.
Currently there is no built in method for this in the Portal. The REST API would currently be the quickest way to achieve what you're trying to do. You can read about it here. You'd need to GET a certain property. Make your small change and then POST it back as new piece of the game config. We'll run this by the dev team for you.