Repeat Serial Outputs

Hi, Recently I buyed a EfComv1.2 shield for arduino, I proved it in my arduino mega and my arduino UNO, I proved it in diferent pins and serial ports, always with the same result. In the serial monitor the outputs are repeated every second or less. I upload a video in youtube:

Anyone can guide me to what is the problem? I think it's not a connection problem, I followed some tutorials with no result. How I can fix it? Thank you very much in advance,