MNH Fine C4 With Straight Edge And Sackville 1932 Cancel On Gum Side

Has anyone seen anything like this before?

Can you show an image of the front? Is the gum still intact? It's quite well placed so my first suspicion is a philatelic creation but I'm interested in other thoughts.

Edit: Also is there any residue or anything suspect on the front side? Like perhaps it was affixed to an envelope on the front side in some manner?

Yes your absolutely correct I wondered what it was and now that you say that it certainly was attached to something not quite like a hinge mark but more like a tack mark ill send a pic from the front right away. Look at the date on the 2 of 1932 there is a glue mark

As well as under the 9 in a seperate "blob" barely noticeable hopefully the scan bears some fruit on your end

The cancel date for this stamp is one day before the economic conference. I am assuming this is a philatelically contrived item marking the last day before the event, and the cancel being on the back because, well, it's a beautiful stamp. Unless, the stamp was printed on the glue, and the cancel on bare paper. The question remains, is the glue intact? And furthermore, if it is intact, on which side is it?

More, this could have been on the seaplane along the route they were using/experimenting with to fly airmail to Ottawa from the UK, in fig. 10 of this pdf. ( http://www.aerophilately.ca/stlaw.pdf ) you can see the seaplane and flying boat travel past the area that your cancel is probably from (Sackville N.B.).