So you are scheduling all these example items to start at the same time but with different durations, I think you have detected a bug in the scheduling software.
This being the case I suggest you file a support request with Auctiva and please post the outcome for others to see.
I always schedule items with the same duration together so would not have noticed this, wonder if it happens if they were incrementally posted i.e. 3.00, 3.01 .. rather than all at once.
Experimentation like that on greedbay is expensive, best file a support request first, meantime you could group them and intiate scheduled post for them in groups by duration.