To restore - write the disk1.img to a 1.44MB floppy disk using a suitable program such as Winimage or Rawrite (or others, the .img file cannot be just copied, it needs to be written
by a program, it is the boot disk for the restore file set)

Boot the Compaq Concerto using the boot disk you made. 

The program that starts the restore is loadall.bat , so you type loadall and hit enter and the restore will begin.

You will need to have the other 13 backup disks copied to floppy disks so they can be used to install. The backup disks just need to be copied with whatever copy program you use.
Make sure to copy only the files in the backup disk folders to floppy, not the backup disk folder. You should probably label the disks to keep them in order.

After you finish the restore then remove the floppy disk. Reboot the Concerto from the hard drive (just turn on the computer) and you have a fresh Compaq Concerto.

The diagnostics.ima is the diagnostics disk for the Concerto, it is in German. Those files are also in the compaq diagnostics directory. 

The original backup are the files that were provided in this post from The Vintage Computer Forum

http://www.vintage-computer.com/vcforum/showthread.php?26914-Windows-for-Pen-for-Compaq-Concerto

If you have problems you should read the information in that forum.

I do not own a Compaq Concerto.