I have a Duemilanove with one 16 MHz crystal. It has a FTDIO as USB serial.
Then I have a Uno rev3 with a CSTCE16M0V53-R0 resonator attached to the a328 and a atmega16u2 as USB serial with a much larger 16 MHz crystal in metal housing attached to it.
Why are the resonators different? Why not use the same type for both controllers?
I have never tried but is it not possible to let both microcontrollers use the one and same resonator?
Could the board be production optimized or is there a reason for this different choise of components?