Do you need another sort of dupe, where you either don't accept pings from the previous address, or possibly evaluate the ping to see whether it's still a dupe? Not only do you have cases like this, where you never want to accept a ping from the old address, you also have the potential for situations where someone moves from a blogspot subdomain to a new address, so you dupe them to the new URL, and then someone else moves into the blogspot subdomain, and their pings get counted as updates for the previous owner. My first instinct would be to look at the blog name in the ping to see if it has changed from what it was at the time of the forward, but then if someone runs a poller that grabs the blog name from the HTML, you would end up thinking it changed hands when the page went from dead to a 404. Hrm.

yes, the current duplication handling is pretty sub-optimal for this. just moving the subscriptions over to the new name, and keeping around the old url and name for ignoring pings until the name changes would probably be a safer way to go.

but the problem here is entirely on the weblogs.com side. it looks like dan's moveable type blog is pinging weblogs.com, but then someone/something else is pinging it at spurious times, and the advertising on the page fools the update-verifier into thinking it has been updated. my main frustration is just that since the spurious updates are coming through weblogs.com, there's not much i can do to track them. (although the name may be key here, too.)

eventually the spurious updates will bug me enough to track them down.