Purpose of storing multiple Kindle serial numbers?

[cyraxote]

I'm not sure I understand the point of having multiple numbers. Is it simply that if I have more than one Kindle device, any books that are imported in Calibre will be readable on any device? Does it matter that one is a Voyage and the other is a Paperwhite Signature? If I get rid of a device, is there any real reason to get rid of that serial number in DeDRM?

Thanks.

[ElleKayEm]

Yes. No. And no.

[cyraxote]

Appreciate the brevity. :)

[cyraxote]

And here's a follow-up question: are books bought at Amazon associated by them with particular serial numbers, say whichever device is your default when you buy the book?

[ElleKayEm]

No, each copy of a book will have DRM associated with the Kindle it's downloaded to. Or if you download from the website, whichever Kindle you choose then. The encryption keys for E-ink Kindles are derived from their serial numbers. If you download a book with Kindle for PC/Mac, DeDRM gets that app's key from where it's stored on your computer.