I proceeded this way:
1/ Install a base beta version of 19.10 (or the same version of the system you are willing to clone) on the installed SSD drive, making sure it dual boots correctly.
There are many walthroughs; here is an example.
2/ Proceed with CloneZilla
as of this walkthrough.
Download Clonezilla stable ISO or Direct Download clonezilla-live-*.iso
Make a bootable (Live) USB using Startup Disk Creator.
Boot from the created Clonezilla media.
Now you have many options :
Create an image of only '/' (saveparts) and clone it to any partition
of your other SDD.
Create an image of the full disk (savedisk) and clone it to your new
Create an image of a partition and clone it to your new SSD
(I used the third option) - note: if your SSD is smaller look here.
Be prepared, the CloneZilla lingo is a bit cryptic, but very logically organized, be sure to understand what you do at each step:
As of above, select the option that allows to copy partitions, save it (my 19.10 install has only one partition) to an external USB drive (saving images doesn't erase the contents of the drive, just make sure you have enough free space for a whole partition's image).
3/ Now once your freshly inserted SSD drive is working, proceed with restoring the partition where it belongs:
Be sure to know which target partition you are aiming at for the restoration, use Gparted or Disks to that purpose, write down which partition you are aiming at (your root / partition /dev/sda5 in my case) on your new system, and proceed with rebooting with CloneZilla
Now select the options to restore an image from the USB drive to the target partition on your new system.
4/ Once this is done, you have to reinstall Grub 2.
I personnally use Boot-repair. Make sure you run it from UEFI on your new system.
(I had an issue that I could not install boot-repair from the 19.10 beta live iso for some reason. Tip: I used a Linux Mint Cinnamon iso where it is installed by default, and proceeded fixing grub there).
As a consequence, my 19.10 dev is working as well as of the previous disk.
Note: as this walkthrough is present on many other locations, I only redirect to existing ones, just detailing the steps I followed for a specific Ubuntu solution.
Note: you may have to edit etc/fstabs, but I didn't have to using Boot-repair.
Just in case, if you experience boot issues after SUCCESSFULLY running boot-repair
(always check rebooting first) the Ubuntu doc for Boot-repair specifies as follows:
If after using Boot-repair, you experience boot issues, you have to add the following line to the /etc/fstab in order for the future grub-install commands run appropriatedly:
UUID=XXXX-XXXX /boot/efi vfat umask=0077 0 1
The value XXXX-YYYY is to replace by what will have been returned by the below command, by replacing EFI by the appropriate value (you will know by opening the file for edition):
sudo blkid | grep EFI
If, despite all of your attempts, the repair does not work, the forum is there to help you!