Post your questions, suggestions and experiences regarding game design, integration of external libraries here. For irrEdit, irrXML and irrKlang, see the ambiera forums
You could use a .irr or Collada scene file. Both are not directly exportable IMHO, but you can write them on your own - it's simply copy and paste once you have it. Moreover, you could also create the one mesh you want to duplicate and use irrEdit to create the scene.