When moving a card between widgets you will have the option to either commit a card to another widget or to move it to that widget. The commit function will duplicate the card and a relation will be displayed on the card.
To set your default value click your avatar in the top right corner, go to Edit Profile and Preferences.
You will always have the ability to override your default value.
- Holding down control/command when moving the card will force a commit.
- Holding down shift will force a move.