Cloning with Clonezilla
I suggest that you download the current stable iso file of Clonezilla from
www.clonezilla.org/
Read the documents about it and try. Create a CD/DVD/USB boot drive from the iso file and boot into Clonezilla when you have connected both the original source drive and the new target drive (intended to become a cloned copy).
It is not too difficult, I would say much easier than to use pinguy bullder.
If your internal drive is easy to remove
"... so i really need the second external drive to be a replica of the laptop drive ..."
In this case you can use Clonezilla to clone the whole drive, which is one option. Other options are cloning one or more partitions and creating an image (a directory with a number of files, where the big files are compressed).
If you clone the whole drive, for example /dev/sda with Clonezilla into a target drive of the same kind and at least the same size as the source drive, the target drive will work, when it is replacing the original drive. But do not boot the system from one of these drives, when both are connected.
Testing
It is straightforward to test that you really have a working cloned copy - a replica. Replace the original drive with the cloned copy, boot and test that important things work correctly.
If your internal drive is difficult or impossible to remove
"On this family of laptop you have to remove the optical drive, remove the base panel, disconect speaker cable and battery cables plus one mother board ribon cable. Too much just to test :-) probably do more damage."
In this case you can use Clonezilla to create an image, a directory with a number of files, where the big files are compressed.
If you make an image of the whole drive, for example /dev/sda with Clonezilla, you can restore it into the original drive or a target drive of the same kind and at least the same size as the source drive. The target drive will work, just like the original drive. But do not boot the system from one of these drives, when both the original drive and a cloned copy are connected.
Testing
It is important to test that the backup is really working. Otherwise you cannot rely on it. In this case it is not straightforward.
'Everything' in the drive is new and you have no personal files in it, for example a single boot Ubuntu system:
Take the risk of overwriting the original internal drive - Use Clonezilla to restore from the backup image to the original internal drive.
Boot and test that important things work correctly.
There are important personal files in your single boot Ubuntu system:
Copy (backup) your important personal files to another drive, where you can see that the files are there and that you can use them. Use some backup program, or simply copy with the command line or {copy and paste/drag and drop} in your file browser.
After that you can take the risk of overwriting the original internal drive - Use Clonezilla to restore from the backup image to the original internal drive.
Boot and test that important things work correctly.
You have a dual boot system with Ubuntu and another operating system, for example Windows or MacOS in the internal drive:
In this case I think there is no really safe way to test that the Clonezilla image can be used to restore a working system. So I would recommend that you copy your important personal files to another drive, where you can see that the files are there and that you can use them. Use some backup program, or simply copy with the command line or {copy and paste/drag and drop} in your file browser.
Comment
Clonezilla does not make a complete cloned copy like for example dd (or mkusb, which wraps a safety belt around dd). Instead Clonezilla copies only the used blocks (where the bootloader, partition table, file system overhead, the files and directories are stored), and skips the free blocks. This makes Clonezilla much faster than dd, particularly when there is a lot of free space in the partitions.
