A couple of ways to tell. If you have a store with a section configured to “New Listings”, they won’t show up there when relisted, and when you use Automatic Restart, they are not there. Easier way is to go to any of your items and select “see other items” link, then sort by “Newly Listed”. Relisted items are buried with their original date.
I had requested this feature as well but I suspect there may be a limited amount of calls to the Additem vs the Relistitem API. I don’t really know.