I'm not sure how the device info is determined for User Signs-ins, but I'm seeing the interesting combo of OS:WindowsPhone and Browser:Android 4.0 ! Not sure which I want to believe, as neither are attractive propositions now.
Those might be standard "template" values used by different clients. For example, PowerShell is a common "offender", or EWS-based clients - I can see few logins from Windows 8 and IE 7.0 in my logs, which I haven't used for years now. Just ignore them.