why does this code execute twice in quick succession, pray?

if (now.minute() == 59 && now.second() == 30) 
  {
    if (SetRTC == 0)
    {
      SetRTC = 1;
      Serial.println("Syncing the clock ready for the pips: ");
      Serial.println();
    }
  }

Is the block of code in that conditional getting executing twice as well?