Cloning Raspberry Pi SD cards can be done via the rpi-clone script. Rpi-clone comes pre-installed on all Andino SD cards.
First, plug in the SD card that should be cloned to using a USB card reader and plug the reader into the Raspberry Pi. Then, identify the SD card using dmesg. In our case, the SD card that will be cloned to is sda.
Now, run the script:
sudo ~/rpi-clone/rpi-clone.sh -f sda
When asked if you want to initialize the disk, accept by typing yes:
Do you want to initialize the destination disk /dev/sda? (yes/no): yes
When prompted, enter boot as the label for the rootfs:
You may enter a label for the destination rootfs /dev/sda2: boot
Finally, accept to run the clone:
Final check, is it Ok to proceed with the clone (yes/no)?: yes
When the cloning process is finished, unmount the partition by hitting enter when prompted. You can now remove the SD card from the card reader.
Shut down the Raspberry Pi and boot from the new SD card to check if the cloning process was successful.