I've seen the reports on the internet about duplicate android ids (eg. Is there a unique Android device ID? ). They're mostly from 2010, with a couple of updates saying it was still broken in 2011. But what's happened since then? Are there still a lot of devices out there with duplicate IDs, or did OS updates fix them?
(side note: yes, there are other options, like the serial number and telephony id, but there are also reports of those values being unreliable.)
I only need to support 4.0+ (api 15), so if the problem is guaranteed to be fixed there I will be very happy. :)
UPDATE: I found https://code.google.com/p/android/issues/detail?id=10639 which strongly suggests that devices shipped with >=2.3 are fine, but what about devices shipped with 2.2 and then upgraded? And what about the reports that phones were still broken in 2011 - possibly after 2.3 was released? I hope that those reports were just un-upgraded phones, but I want to be sure.