I found that I created two separate branches, when I created an ancestor branch for a male and his wife, and another independent branch for a female and her husband. It turned out that the two couples were actually the same one!
One way to catch this, is to always go to "name search" and see if the name is already listed. However, when adding hundreds of names...to check name duplicates would take hours for FTB to run the names with that function.
I also use Family Tree software from MyHeritage.com...as I add names, the software automatically asks whether or not the duplicate name is the same person. This prevents parallel branches from being completely separated from each other.
Is there a way to automatically check for duplicate entries in Ancestory.com-FTB?