you can reproduce the error by doing the following:
1.point your browser to the online booking example; url:"http://seam.demo.jboss.com/"
3. press button "find hotels"
4. click (and position the cursor) in the input field for the search string
5. press "return" on your keyboard
java.lang.IllegalStateException: Client-id : _id0 is duplicated in the faces tree.
This has been discussed here *many* times. It is a bug in MyFaces.