I don't know where you're going with this.... Diablo (and others games) use "continuous saving" meaning that save occurs as soon as you change something on your char and especially if you trade or drop something on the ground... So, altought your theory is plausible, it doesn't apply in this case.
In my opinion, I much more believe in "packets alterations" sent to diablo servers in order to bring them in a unstable state. From there, validations and security features might not trigger properly. This is when the "Hackers" would send "false actions" to provoke a dupe items. There's so many situations this could be done. Someone, somewhere found one. Just like I respect a prisoneer that managed to espace prison, I have respect for those hacker guys... I don't appreciate it, I just respect them!