I was talking abot a bug in WD/X5 which did not allow placing multiple head placeholder objects on one page. If you try to do thin in X5 you'll end up with some garbage in the resulting HTML. This is fixed in WD6. So if you place multiple placeholder objects which all have the "<head>" name on the same page or on the pasteboard beside it, the content of all these will be concatenated and correctly inserted into the head section of the exported page.
This may be useful if you have some code common for all pages so that you can use repeating object and add some page specific code in the separate head placeholder. Besides, using multiple placeholders may help to organize your snippets better.