The easy way to copy a card is using the filmstrip.
To do this, follow these steps:
Right click on the card you want to copy and choose Copy. (You can also use Cmd/Ctrl-C to copy).
You can then select multiple cards using shift and copy them all at once, or select them all using Cmd/Ctrl-A.
Then, open the new gamma.
Click anywhere on the background of the new gamma.
Lastly, hit Cmd/Ctrl-V to paste. Your cards should appear at the bottom of the new presentation.
