I think only P has dual serial ports, check data sheet to be sure.
avrdude: ERROR: address 0x1f010 out of range at line 2 of ATmegaBOOT_644P.hex
avrdude -pm644p -c avrisp -b 19200 -P /dev/ttyUSB0 -e -u -U lock:w:0x3f:m -U efuse:w:0xFD:m -U hfuse:w:0xDE:m -U lfuse:w:0xFF:mavrdude -pm644p -c avrisp -b 19200 -P /dev/ttyUSB0 -U flash:w:optiboot_atmega644p.hex:i -U lock:w:0x2f:m
and signature bytes
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