adding modified design.rb for sloving dup prob

app/models/design.rb

@@ -36,9 +36,11 @@ class Design
   def files=(attrs)
     files = eval(attrs.last)
     attrs[0].each do |a|
+      if(a[:id].nil?)
         files.build(:file => a[:file], :to_save => true)
       end
     end
+  end
   
   protected
   def cleanup_empty_fields