There are a few things, that have changed over a few years ago:
• Frequently asked questions about two-step verification for Apple ID - Apple Support
• About two-step verification and SMS - Apple Support
• Two-factor authentication for Apple ID - Apple Support
You could choose to limit your number of AppleIDs to one AppleID; if you have two.
They can be combined; I've only the one. Don't see a need at the moment for more.
Unless your situation has changed by intent or accident.
Apple ID FAQs - Apple US:
https://appleid.apple.com/#!&page=faq
Recover your AppleID - Apple:
https://iforgot.apple.com/password/verify/appleid#!§ion=password
This has been a problem for a few years; there are newer solutions to some, now:
http://www.engadget.com/2011/06/17/multiple-apple-ids-frustrated-by-apples-no-co nsolidation-policy/
Even if someone's old AppleID is based on a non-working email address, that can
be changed; Apple support has articles and if you happen to have a newer product
their better help is free, if you can ask them a question that relates to the newest one.
Sometimes an older password will have been too easy for something or someone to guess.
An automated system that can run through dozens of probable combinations a second, a
bit like an automated phone dialer, but more sophisticated, can eventually guess many.
So it is a good idea to change your login passwords & use juxtapositions of letter/number.
A little more than a year ago, when I bought a newer product from Apple, and sought to
use it, my password was deemed not secure; in the process of changing it & then found
my name associated with features I'd no intention of using, (it signed me up to iCloud, etc)
I had to change the password again to one more complex than previous. And for some
reason, Apple system treated it like an all-new AppleID; though account was unaffected.
There is quite a bit of fiscal investment by some sleuthing for private information and some
of them are not supposed to be doing that under rules of law. Others have paralegal rights
to think they can do so, and then there are those adware scams where people give up all
their passwords and computer or device access instead of learning how to remove popups.
Because there are several angles, the simple things involve user-secure practices to avoid
the bad guys from getting an edge. And avoid giving away too many different pieces of the
puzzle online because they can be easily interlocked again because computers do that.
(Avoid calling a phone number in a scam popup message on the computer, for example;
the hold-hostage scam initially is easily ignored by force-quite of the browser; then launch
the browser with extensions disabled; or with internet access physically turned off.)
Anyway, I'm not sure I answered any question, but the links above do explain the newer
aspects of security in relationship between devices and Macs; and sharing info between
them is also an area where one has to be careful. Avoid selling or giving away a device
or a computer unless you've actually made it ready for resale; per Apple support articles.
Hopefully you'll get adequate replies to the question(s) you pose here.
Good luck in this matter! 🙂
