Hi David,
You are right there is a bug there. I think this is an issue where I ran into a problem and came up with a cheap solution and got side tracked and forgot about coming back to it to make a better solution.
The issue as I recall is that in using the multi sites feature, these same content templates are used when creating default content for child sites. So we get a clash because the pageguid is already in use in the first site and can't be used again in child sites.
I will change the logic to only generate a new page guid if there is already an exsiting page with the same guid. I will add logic to check if the parentGuid is a page in the current site or not.
It still will not be a perfect solution because it will really only work correctly in the first site in terms of hooking up the parent page.
Best,
Joe