If you have a template containing something like the following:
{Navigator template='foo'}
{* this is a comment about Navigator *}

Then you export the design, then import it, it will change the template to
something like:
{Navigator template='foo'}
{* this is a comment about Navigator * template='foo'}

Which results in broken code, because the comment isn't closed.

The key is the word 'Navigator' in the comment, the xml export/import seems to
think it's a Navigator call and adds the default Navigator template to the end
of it.

Suggested fix:
always ignore anything in comments