How to reproduce :

• create a model to modify a color which appears in lot of css files with the same id : default.default.contrast.dark
• add one of them like this :

  a:link,
  a:visited {
      color:#AD1700/* AMETYS ("default.default.contrast.dark") */;
      text-decoration: none;
  }

  > when you open the skin factory, the menu corresponding to this id is broken