The clerk 'accidentily' printing off a second ticket is really no different than someone else picking the same numbers 1,000 miles away somewhere else. If the clerk prints off an 'extra' copy of your numbers, and they are losers, do you owe the clerk any money ? No. What if you ran in the store just before the deadline, bought a pre-printed ticket (and it was really a duplicate of somebody else's ticket bought earlier), and it won, would you complain ? No. Would you hand your winnings to the original ticket buyer ? I think not.
They are not 'your' numbers, they are public domain. It would be no different than the folks that post predictions HERE, someone seeing someone else's numbers, using them, changing ONE number, and playing them (and winning). Are you obligated to share ? NO. Is 'sharing' the right thing to do ? Probably not: because when will it stop ? If 15 people pick numbers 5-10-30, and different combinations for the other two numbers, and I happen to pick 5-10-30 and the CORRECT combo for the other two, must I share with 15 other people ? No.
As far as letting someone else in a line ahead of you and them hitting the winners, you are entitled to ZIP because YOU let them in. It would be no different than if you picked the winners - are you going to share with the person that was in line BEHIND you ? I don't think so.
How many times have you stepped away from a slot machine in a Casino, the next person behind you steps in and wins ? Do you think they 'owe' you ? If you do, you have rocks in your head.
This is why they call all of this 'gambling' - you pays yer money and takes yer chances - and you lose 97% of the time - or more.
Some folks appear to be letting 'wishful thinking' get ahead of common sense and reality - especially with large sums of money. There is a word for these kinds of people, and that word is 'broke' - 'sucker' - 'fool' - or something along those lines.