The Dup Key settings are used for 5250-based (Genie) applications that use the DUP keyword, and by Rich Display File applications that utilize the "allow dup key" and "dup key response" properties. They determine the JavaScript key code (the default key is Shift-Insert) and the Dup character to use within input fields.
Example:
// Use a unicode character that looks like a round circle for the Dup character pui["dup"]["char"] = "\u25CF"; // Set up Shift-Insert as the Dup Key pui["dup"]["keyCode"] = 45; // Key code for the Insert key pui["dup"]["shift"] = true; pui["dup"]["ctrl"] = false; pui["dup"]["alt"] = false;
Where do you save this configuration option? Here.