A Modern Day Postage Due Payment?

Just wondering if someone can explain this. It has a Rochester, NY machine cancel from October 15, 1991 and was overlaid with a second 29 cent Basketball commemorative stamp and a hand cancel from Castle Point, NY 9 days later on October 24, 1991, which slightly overlaps the original cancel.



My assumption is that this paid for a postage due article requiring the second stamp. Or is there another explanation? A 9-day wait to get a parcel from one part of NY to the other, seems like a long time. Maybe it was waiting at the post office for someone to pay the postage due?

Perhaps postage for return service?

Perhaps forwarding the letter to a new address?

I've seen similar envelopes where documents were posted (for checking, a signature, etc) and the same envelope was used for return post with a sticky label over the address. Sorry, don't have scans or any in my possession.