hansibull:
you can use the EEPROM24 library.
I've used it a lot and it's easy to interface with, and doesn't take a lot of space either.
you can download it here: http://rweather.github.io/arduinolibs/classEEPROM24.html
So I think this library can work only for the 1 Eeprom = 1 device Eeprom style.
No for for the 1 Eeprom = 2 devices Eeprom style.
I'm really confused about this.