2 (or more) PN532 modules. compare correcr cards on correct reader

Projects Programming
5 
bool compareArrays(uint8_t arr1[], uint8_t arr2[], int length) {
 for (int i = 0; i < length; i++) {
  Serial.print(arr1[i] );
 }
       Serial.print (" : "); 
 for (int i = 0; i < length; i++) {
  Serial.print(arr2[i] );
 }
        Serial.println ("  "); 
  for (int i = 0; i < length; i++) {
    if (arr1[i] != arr2[i]) {
     
      return false;

    }
  }
   Serial.println("true");
  return true;
}

i get :

1600734 : 162306181
1600494 : 67252107169

why?