is SystemInfo.deviceUniqueIdentifier changes in diffrent unity versions?

In the latest Unity version (5.6.1f1), the “SystemInfo.deviceUniqueIdentifier” property, returned a different string then in the previous Unity version (5.5). The test was in the editor. Will this also happen on device builds? (IOS, Android)
I use this string to login users as “guests”, and that’s a lot of users, so this matter is urgent. Please help

Did you ever find a fix? I am in the same boat and have no clue on a fix.