Strange behaviour on Avast Anti-Theft

My phone was stolen yesterday, and I’ve been looking on avast anti-theft screen since, to block it as soon as the thieves turn it on. Today I’ve logged in to find that there was 2 Nexus 5 (my stolen phone) and I can’t access info on any of my phones, even the ones which weren’t stolen, is that a bug or the thieves have managed to bypass avast’s protection? Im really concerned right now.

This is what Im looking at:

https://fbcdn-sphotos-a-a.akamaihd.net/hphotos-ak-xaf1/t31.0-8/1397563_1495301634066814_990630423702620717_o.jpg

The thief can flash new ROM on the device, but in this case there will not be two devices; are both of them the same device? Can you please post the screenshot? Thanks…