It looks like v6.5 had a bug where it was allowing an invalid time display, and has been fixed since then. Since 00:00 PM is an invalid time, it's not likely you'll be able to trick the system into displaying it.
Since the default is 23:59, I'm not even sure how you're seeing 00:00 AM for the value when it's clearly supposed to be reading 11:59 PM.
I would export the syntax of the original 6.5 datawindow, and the 10.5 version (after you edit and save it) to see what the differences are.
If you create a new datawindow, with a similar time field and defaults, do you still see the wrong value being displayed when you insert a row in the datawindow painter?