Is there a shortcut for Duplicate Line command in Visual Studio 2008?
Some similar examples:
For Visual Studio Code 2019:
Edit menu keyboard shortcuts with: ctrl+k and ctrl+s
Edit "Copy Line Down" (Shift + Alt + DownArrow) to your your own shortcut.
You can find it, with the command ID: editor.action.copyLinesDownAction
For me, It's ctrl+d