How can one know if a paper award decision was made with the award committee not having access to the author names? How can one know if a paper award decision was made with the award committee not having access to the author names?

I am mostly interested in machine learning / natural language processing paper awards.
In some cases the award committee or sponsoring organization may describe its procedures on its official website.  Otherwise, you can write to the award committee chair and ask.

I don't think there's any more general way to know.  In particular, I doubt that there is any central place where you can find this information for many different awards.  (It would be a pain for someone to collect it and keep it up to date.)