Default two different Xperia sp but same mac-adresse

Hi guys,
my gf recently bought a Xperia SP and for an unknown reason my SP and her's have the same mac-adresse and because of that the same ip-adresse when connected to the same wifi
Both devices have Existenz 4.0 installed and bootloader unlocked (on 3.3 the issue was there too)
So two questions:
- Is it possible that I accidentaly changed the mac-adresse of one device?
- What to do now? Contact Sony or try to change it manually?

I'm really confused