You have gotten some good answers, but the most obvious, and the recommended first measure wasn't mentioned:

Tell your users to not click twice.

If you just put a little text saying "this will take a litle while, please do not click more than once on this button", you will get rid of 90% of the problem, or more.

You still should have some kind of fallback in the code, as suggested and shown, but this is where you start.

I also don't really know what you mean with "nor to use more cookies", especially the word "more" confuses me. If you can set some cookies (which the word implies), there is no hindrance at all for you to add more, is there?

You have moved into a dark place.
It is pitch black. You are likely to be eaten by an ant.

In reply to Re: Avoiding a second click by Dog and Pony
in thread Avoiding a second click by MMilani

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