I am using 2 ethernet shields and they both show up with the same MAC address, I have tried to change one with no luck.
these are the lines I added to the sketch to change the address.
byte mac[] = {0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED};
IPAddress ip(192, 168, 1, 19);
Blynk.begin(auth, mac, ip);
Please consult Arduino_Ethernet_Manual example for all parameters.
@tbarritt. I had the same problem here. I managed to solve only changing the MAC address.
Byte arduino_mac [] = {0xDE, 0xED, 0xFE, 0xBA, 0xAE, 0xEF};
…
Blynk.begin (auth, "blynk-cloud.com ", 8442, arduino_mac);
I hope I helped you.
Hugs
Julio