I think this is because you had the auto-dedup option set on the My Video folder, this is great on Some series folders - especially kid series allowing me to find the correct episode of Bitz and Bob from my granddaughters description, but much less helpful for one off programmes as you have discovered.
It is an option that it well worth experimenting with the manual version via the Opt+ option to see if works sensibly for a series before using the auto version.
AFAIK the original names are lost forever and the only option is tedious renaming of each recording (opt+ menu) unless someone could think a way of using the recording date/time and channel to search some archive to find the original recording title - perhaps activity.log has enough information
thanks for your thoughts on this. I did do a back up of my 1tb drive by taking it out and connecting it to a SATA connector and using linux reader on an external HDD. However, it didn't detect all the files and I think that the 1tb has more recordings on it than my backup. When I look at the backup - I can see 3 types of file: the .ts, the .thm and the .nts - but I think there should be 4?
so here's what I'm thinking of doing:
1. install the 2tb drive into the machine
2. follow your very helpful 'set-up' guide to make sure 2tb drive is all set up
3. Copy across the backup files from the external HDD - I think you suggested using USB rather than FTP - would USB be quicker?
4. If I've understood correctly, they won't work straight away, but by having 'auto-decrypt' - those files should then decrypt over the next day or so - as they still have their 'name' attached to the file - they may work (although I believe that they're missing one of their sidecar files - not sure if that will make a difference?)
5. If those work, I can then copy any remaining files that are still on my 1tb drive (and are not on the external HDD) using SATA and the usb (or FTP) and rename those missing files.
by the way - I note your comment about keeping it plugged in via USB - but with a 4 year old in destructive mode running around the house, not sure that would last very long...
thanks!