Portuguese Stamp Printed On Postcard.

I hope you're all right.

I have a piece of cardboard with 3 stamps attached. Two had a strong seal, so I decided to take them out by putting them in hot water .... As soon as I heated the water, two left the paper, but the third one did´nt came off ......,
I returned the card with the stamp in the hot water, but it didn't come out ...
I examined it better and saw that it was not a common seal but a seal printed on the paper and without perforations, being an integral part of the paper.

I would like an opinion if this printed stamp has any value greater than the catalog stamp
(Scott 619 / Michel 632).
Can someone give me a light about it?

Thanks a lot.
Wagner

It's what is called "postal stationery", i.e. an envelope or card pre-printed and thus pre-paid. In so far as people collect them, they usually do so as entire envelopes or cards, and those that have been cut or torn out generally have little or no value.

OK, thank you very much for the answer.
I'll keep it for being a unique piece.