I think these two different people have been merged too many times, since there's information that is repeated a few times, but slightly different each time. How do I go about fixing this problem?
Here is a link to an article about merging duplicates. At the bottom of the article are links to other articles that may help.
Keep in mind that there are often people with the same names. You may need to unmerge if there really are people with the same names that have been merged. I personally had 2 cousins that were close in age, born in the same place, their names were close and they used the same nickname and they married women with the same first name. They were always being merged together until I documented them and added reason statements explaining the circumstances. Look at the sources and make sure the sources go with the correct people.
Here is a link to an article if you need to unmerge.
You have a big job ahead of you but it can be very fun like a puzzle.