One of the biggest challenges of genealogical research is the the unknown ancestor with the common name. Differentiating between people with the same or similar names, especially those that live in the same area, can be a daunting and seemingly impossible challenge. However, since no two objects can occupy the same place at the same time (at least in our macro-atomic world), there should be a way to differentiate between these people and pick out the correct ancestor. Fortunately, there are some methods that work most of the time.
First, I am not talking about the endless instances where I find pedigrees ending with a "Mary, b. abt 1800 in Ohio." Many of these instances are merely evidence of incomplete or sloppy research, especially when the entry, as is the case most of the time, is unaccompanied by any source citations that could give a subsequent researcher some idea what has been done previously. In addition, anyone who thinks that they have the identity of such a person established needs to explain exactly how and why they came to that conclusion. It certainly is possible to come to the end-of-a-line with little or no information identifying a wife, other than a mention of her first name in a will or other document, but any such entry should be accompanied by the evidence that does exist and certainly accompanied by copies of the document or documents.
Now, back to the initial issue, the multiple identity problem. This problem is most commonly found in Scandinavian countries, Wales or other places were the pool of surnames is either missing because of patronymics or severely limited. In times past, genealogists who encountered this type of problem, especially in small towns, have simply assumed that everyone in the town with the same surname was a relative of some sort and included them all, as individuals, in the accumulated family group records without any particular effort evidenced in sorting them all out into families or pedigrees. I have seen this happen more than once with the research done by some of my own ancestors. Whether or not you inherit this problem or encounter it yourself, the challenge is about the same.
Immediately upon determining that this situation exists, the research should begin backtracking to the first positively documented and identified ancestor in that particular line, rather than banging repeatedly into the issue. The research of this identified ancestor should be expanded sideways to learn everything possible about the ancestor's family, neighbors, friends, occupation, religion, education, material possessions. Every type of record available in the area where this identified ancestor should be carefully examined. Further, the researcher should become very well acquainted with the history of the area where the identified ancestor lived. Every history of the area should be carefully examined for clues. It is reasonable to expect that this more in-depth type of research will result in the problem of multiple individuals with the same name being resolved in the process. The main theme of the investigation should be to identify, as much as possible the exact location of each family in the community. This is particularly true in Scandinavian countries, but the same methodology applies to countries such as Wales.
As the information is gathered, it must be organized in a way that provides a way to see the way the families are distinguished. I have heard several ways this can be accomplished. With today's technology, it is possible to construct a spreadsheet with all the candidate individuals listed and then compare the facts concerning the the individual facts obtained by the research in columns so they can be compared and the individuals eliminated by the research easily marked
I usually hear some kind of claim in these situations that the researcher or researchers have "search every record available." If this were even possibly true, then they must conclude they have come to a legitimate end of line. It is not acceptable in these situations to "adopt" an ancestor merely because separating the similarly named individuals is difficult. In almost all of these cases the possibility of continuing depends on the time-frame involved. If we are talking about ancestors back into the 1600s or further back in time, it may be the case that the records do not exist to make the determination. But the same rule applies to backing up to the descendants and doing more in depth research.