How to handle multiple instance of “send_to_editor” js function

only overwrite the send_to_editor function when your link or button is click but store the old function to restore it so try this on a click event:

//store old send to editor function
window.restore_send_to_editor = window.send_to_editor;
//overwrite send to editor function
window.send_to_editor = function(html) {
     var imgurl = jQuery('img',html).attr('src');
     current_item.siblings('.upload_image').val(imgurl);
     current_item.parent().prepend('<div><img width="300" src="'+imgurl+'" alt="banner image" /></div>');
     tb_remove();
     //restore old send to editor function
     window.send_to_editor = window.restore_send_to_editor;
}