Full Sheet Postage Due, Original Gum, But Canceled?

Hi Everyone,
I have a question, I see this sheet of 3 cent postage due and the seller says it has original gum on the backside but the front side looks like it has the wavy lines, like the whole thing has been canceled, and was wondering if this is true, how did that happen?

Thank you, here is the photo:
SueStamps

hard to tell with such a small scan.
looks canceled, might have been precanceled but not used.

How interesting.
I didn't know that a whole sheet could be canceled at once.
Thank you so much,
SueStamps

I have had several of them before. As far as I know they were intentionally postmarked to document the postage due fees collected and forwarded to their supervisory office. When cancelled by the sheet, they were typically documenting a large mass mailing or bulk rate shipment upon which extra fees were collected.

As far as I know there is no premium to retain these postage due stamps by the sheet, so the ones I had were simply reduced to blocks of stamps for easier storage. Now I have hundreds of blocks of similar stamps -- all postmarked but with original gum.

Hi wt1,
Everything you say, makes so much sense.
Thank you and thank you also StampVirgin, so much for your replies.

You have helped me understand.
SueStamps