ICSP questions

[anishkgt]

Hi All,

I am trying to add the ATmega16U2 to my project for communication via USB. I am in doubt if i should have the ISCP header for the USB and the ATmega328 as well. I was thinking of the using the FTDI interface but the atmel was cheaper so went with that. The arduino schematic(https://www.arduino.cc/en/uploads/Main/Arduino_Uno_Rev3-schematic.pdf) uses two sets of these headers one for the ATmega328 and the Atmel16U2.

Question:
Should i be using for both or just from the ATmega would be ok. What is the reason for having at the USB side as well ?