Yeah, people pretty much have free reign to add things whenever they want. I know there were at one time several Jesus Christ and Mary Magdalene marriages recorded.
It's kind of funny...my inlaws are huge into family history and indexing. They even participated in that event a couple of years ago where they were trying to hit a certain number over a week or weekend or something. Anyway, they aren't listed as DH's parents. He has no family listed in his tree.
Here's what the help section has to say about duplication of ordinances:
When you prepare to perform ordinances for a person, you should ensure that the ordinances are not complete.
President Gordon B. Hinckley said:
One of the most troublesome aspects of our temple activity is that as we get more and more temples scattered across the earth there is duplication of effort in proxy work. People in various nations simultaneously work on the same family lines and come up with the same names. They do not know that those in other areas are doing the same thing. We, therefore, have been engaged for some time in a very difficult undertaking. To avoid such duplication, the solution lies in complex computer technology (“Opening Remarks,” Ensign, Nov. 2005, pp. 5–6).
Family Tree is designed to prevent duplication of ordinances in these ways:
It contains the most recent information about temple ordinances. Information about completed ordinances is usually added to the system within 24
hours.
If the ordinances of a person are complete, the system prevents them from being performed again.
When you reserve ordinances for a person, Family Tree changes the ordinance status to reserved and posts your contact name along with a date of the reservation. If patrons check the ordinance status for the individual, they see those ordinances as reserved.
Family Tree also identifies possible duplicates. Review possible duplicates carefully to ensure they are indeed duplicates and should be merged or checked as not a match. When duplicates exist, ordinances can be complete for one individual, but not the other individual. If the merge process is not completed correctly, the ordinances can be dropped and not included on the final merged record. Please carefully review these articles for more information on merging: Merging duplicate records in Family Tree (53952), An individual is in my Temple Ordinances list, but I found a duplicate record showing ordinances completed (53593), and Checking possible duplicates even when the ordinances seem ready to do (53672).
You can find ordinances you want to perform already complete or reserved. Please honor the work of others. Do not add duplicate records into the system just so you can perform the ordinances. Avoid duplication of ordinances, however well meaning.
I also thought this part was interesting:
What is the 110 year policy, and why was it initiated?
Policy
Church policy states that you may do ordinances for your own deceased spouse, child, parent, or sibling, but please consider the wishes of other close living relatives, especially a living spouse.
For individuals born within the last 110 years, if you are related but not a spouse, child, parent, or sibling of the deceased, please obtain permission from the closest living relative before doing the ordinances. The closest living relatives are: an undivorced spouse (the spouse to whom the individual was married when he or she died), an adult child, a parent, or a brother or sister.
Acquiring permission from the closest living relative is a First Presidency temple policy that has existed for many years—long before new.familysearch.org and Family Tree. The purpose of this policy is to prevent offense to close living relatives who do not want temple work done, and to allow temple work to be done by members of the Church who knew and associated with these individuals, and who were close to them.
When temple work is done without following this policy, members who start working on their family history will be upset when they find that a parent, child, or close relative's work has been done by someone they do not know, when they wanted to complete the ordinance work themselves. It is important to be considerate of their feelings.
Acting in conflict with the wishes of the closest living relative can result in bad feelings toward you and the Church. We ask all members to abide by this policy so that the best of feelings can prevail. Give others the gift of a wonderful temple experience with their close relatives. Share the blessings of the temple.