very strange!

Hello all
Firts project i used an arduino mega , a w5100 ethernet shield -clone and one eeprom.shield.
I made the sketch for store in that eeprom some data at some address {360 , 382 , 404 , 426} when i push a button on a web form.
I have these libraries:
#include <EEPROM.h>
#include “EEPROMAnything.h”
#include <Streaming.h>
#include <WebServer.h>
#include “SPI.h”
#include “avr/pgmspace.h”
#include “Ethernet.h”
#include <Wire.h>
Project works very good.

Now i put same sketch on other arduino mega and other w5100 shield but without eeprom shield
I 'm very very surprised when i push the button on the web form, all data are saved well and after reset arduino all data are somwhere in good condition and i can read well like i have a eeprom shield at the same address.
For me is very strange , i’m a beginer and i don’t understand very well what happen.
Can tell me anybody where the data are stored?In arduino or in w5100 shield?
Many thanks in advance!

The mega has EEPROM onboard. http://arduino.cc/en/Reference/EEPROM

many thanks