Unfortunately, it is true. There have a been a few 'discussions' on a few forums on why Ducati do not keep records of the official owners just in case this does happen - but for whatever reason, they don't. I do remember being told when I bought my bike, that "whatever you do, do not lose the red key for your bike as it will cost you big time".
I recently looked to replace the clocks on my Monster for a digital dash and ran into the same problems. Without the clocks, the ECU will not function correctly - they are somehow linked. I made many enquiries on how to get round it and it cannot be done. I thought it slightly ridiculous that with Ducati's racing heritage, that you cannot remove the speedo without having to replace the whole ECU but unfortunately, that is they way it is.
If you are completely stuck, there is a slightly cheaper (and better) way to do it. Replace the ECU with a new computer by
FIM and you can control lots on the bike - rev limit, fuelling, etc etc. It isn't cheap at about £500 but it does mean that the immobiliser is bypassed and you can put whatever clocks you want on the bike. I think that Sigma are the importers in the UK - and it does work as I have done it on my Monster.
Hope this helps
simon