Racetracks On Machins?

I received a piece of mail yesterday from England (containing my newest CSA) but the Machin on the envelope intrigued me. There are two of a newer variety, each of which has two oval shaped holes punched into them. The 'chads' have not been removed, but I was wondering what the purpose of these potential holes could be.
Interestingly the cover, which also included an 18p Machin, was not canceled at all. Are these a form of cancellation?
Any ideas?

They are "security" devices to prevent reuse of stamps.

They've been discussed in a couple of your "Machin" threads -- try the Search button at the top of the page.

Also, lots of good stuff in this thread:
https://goscf.com/t/10785

KirkS

I also received a couple UK postings this week and ironically perfect machine cancel across top row and no cancel on the " racetrack" ones below, Has anyone tried soaking these to see if they can be saved intact?

Thanks Kirk. I'm totally unfamiliar with the world of Machins. That makes sense.
Chris, I may just try, as an experiment. All in the name of philately.

Reports here say they don't soak well (if at all). But I don't remember who said it or what thread it was in

KirkS

They are self adhesives, and most probably the punched sections will separate if you try to soak - that is the point of them, after all! Having said that, I've never tried it myself, so there might be a knack to it.

Race track marks??

I knew they were a form of 'security' marking from information I got from different Machin websites. I was referring to them as 'paperclip' markings because, to me anyway, that is what they resemble.

I think this is the latest thing for security markings and I too have these in my collection.

Chimo

Bujutsu

Well I successfully soaked them off, but yes the adhesive was more stubborn than the older Machin that accompanied them. I guess if you're looking to quickly remove them for reuse, then you'd run into trouble.
But now here I am with 3 Brit stamps, which, if I were dishonest I could reuse. Too bad I live in the colonies.