once1014:
Oh Ok. Aren't they using the same ports or I need to use (set) different one for the two. I have my UNO connected to port COM3. And not sure if I was clear. I meant also running the 2 sketches at the same time.
If you have two boards connected at the same time, they aren't going to be on the same port. Don't have any connected to my laptop right, as I am out at work, but usually my Yun shows up on COM10 and my Leonardo on COM3.
And "running" 2 sketches doesn't mean anything in regard as to how the boards are connected, they run completely independent. The only possible problem could/would be that you don't get a serial response from both on the serial port for debugging output...
Ralf