How many people in the world were named Mary? How about John? William? Joseph? A syndrome is a group of symptoms that characterize a specific disorder. In the larger genealogical community the disorder to consider people with the same name as the same person has reached epidemic proportions. The Same Name - Same Person Syndrome (SN=SP Syndrome) has become an overwhelming genealogical conundrum (a confusing and difficult problem or question). In areas where given names are drawn from a relatively small pool of possibilities, such as in the Scandinavian countries, confusion between individuals with the same name has become so rampant that there is practically no way that some of the research in these areas can be untangled.
The problem grows exponentially as successive generations of children are given the same name, i.e. William Tanner, the son of William Tanner names his son William Tanner and so forth. Certain European naming practices are almost a guarantee of researcher's confusion. For example, if a named child died shortly after birth (or even later on), the next child of the same gender was given the name of the deceased child. In genealogy programs that allow for merging individuals, these children with the same name but different birth dates are very frequently merged as the same person. Ignorance of the naming practice is the excuse given for this sloppy practice.
The only consistent cure for this lamentable condition is to do research in depth beyond searching for names. In addition, merging should be done with knowledge beyond matching names and approximate dates. This issue becomes excessively difficult for those sharing a family tree such as the situation in FamilySearch.org's Family Tree program. Indifferent or unschooled researchers seem all too anxious to merge people without citing even one source or making even a moderate effort to determine if the two people with the same name are really the same person. The fact that these types of changes can be accomplished without citing a supporting source facilitates the problem.
Except for the financial institutions' propensity to use maiden names of grandparents or parents as "security words" there are few practices in the quasi-genealogical view of the complex area of genealogy that can cause more harm to a carefully crafted pedigree than mistakenly assuming that two distinct people are the same. Historically, assigning arbitrary names to people was a some-what common practice. For example, when Native American children were inducted into the boarding school system, they were assigned names from a very small reservoir of English given names. Likewise, in the early days of colonization of the Americas, the Catholic Church assigned Biblical names to all of the "converts." In some cases, every one of the couples in a small town were given the same name: Jose or Maria.
It is interesting that those who design and develop genealogical software have spent so little time concerned about some of the major problems of genealogy, including the SN=SP Syndrome. Merging, in some cases, is automatic and can occur even when the two individuals do not share the same name. This is as it should be except that in the end, the fact that merges can be wrong is not taken fully into account. The programs are beginning to get into the details of merging when they incorporate a "not a match" function.
Unfortunately, the SN=SP Syndrome cannot be self-diagnosed. If you have it, you cannot understand why everyone needs to verify, in depth, each and every instance of combining records