- are the Modified timestamps on those 766 books the same (you may need to tweak the date format to see a 'real' timestamp) and if so are they close to the time at which you upgraded to 0.97.
My Create dates are 'ok' but I don't make any use of create date.
I was using modify date as the secondary key in my Default View Manager configuration, and as the primary key in one of the other 2 View Manager configurations. I still am, but no longer for any useful purpose
ps : I suspect many people don't-use/look-at/care-about Modified Date, from memory its not in the default Book List columns