This is a common issue when using closures in a loop. The editor variable is live and remains set to the last editor. Hence the problem. To fix it you need to use another closure.
for(var i =1; i<=4; i++)
{
var editoritem="#textpad"+i;
$(editoritem).kendoEditor();
(function(editor) {
// paste logic
})($(editoritem).data("kendoEditor"));
}
Here is the updated jsfiddle: http://jsfiddle.net/6dHgV/5/