To copy a SD-Card to another one including all partitions yo can take the following steps:

1. Find out the device name (f.e.: /dev/mmcblk0):
   • see List, partitioning and format drives or
   • see Get a list of partitions or
   • see Get free disk space and partitions
2. Copy the whole card to an imagefile (Backup):

   $> sudo dd if=/dev/mmcblk0 of=backup_pi.img bs=4M

3. Restore the backup image to the other card:

   $> sudo dd of=/dev/mmcblk0 if=backup_pi.img bs=4M