Is "dieselbe Person" also "die gleiche Person" when it is uncertain that they really are the same person?

Question

I am writing about deduplication of person-records in databases. In short, the goal of deduplication is to identify records which refer to the same real world entities and merge them into a single record. In my case these entities are persons.

I think I understand the difference between "dasselbe" and "das gleiche" when it is about things/items. The former refers to physically the same item whereas the latter refers to two items of the same kind. (explained in this post)

I want to express that two persons could be the same, but I'm not certain (yet) that they really are. For example:

Gibt es in Quelle A einen "Max Mustermann" und in Quelle B einen "Maximilian Musterman", stellt sich die Frage ob es sich um dieselbe/die gleiche Person handelt.

Since two database records either refer to the same person or they don't, I'm leaning towards using diesselbe Person.
Unfortunately my confidence got shook: I asked a native speaker and he said that he would write die gleiche Person because it is still uncertain that they really are the same person. He admitted that he is not sure because his answer might be influenced by his knowledge of database deduplication, where it is technically correct to say "Person A and Person B are 90% the same"*

So my questions are:

• Is there a difference between diesselbe Person and die gleiche Person?
• Can a person even be die gleiche as another person? What exactly would that mean, given that there can't be "two persons of the same kind" when it comes to a person's identity?
• Is there a rule I can use? I'm not sure if the "dasselbe/das gleiche"-rules can be applied here in the same way.

Any help is appreciated, thank you.

_{* Another way of saying that would be: "Person A is the same as Person B with a certainty of 90%".
This means, that the sum of calculated similarities between the two person's attributes (e.g. firstname, lastname and gender) is 90%.}

Answer 1

I will attempt to answer this question although I don't think that everyone would agree to me.

I would personally, without any knowledge of deduplication of person-records in databases, tend to use "dieselbe Person" instead of "die gleiche Person".

This is partly due to what you yourself have asked about the question:

Can a person even be die gleiche as another person? What exactly would that mean, given that there can't be "two persons of the same kind" when it comes to a person's identity?

The argument of using "dieselbe" and "die Gleiche" is one that you have seemingly understood, and hence, I would support your (rhetorical) question of "how can you even have zwei gleiche Personen?

If you talk about zwei gleiche Personen, there would have to be additional context to justify your argument. If two people can be gleich, then this should refer to a certain aspect, or in this case, a group of aspects which have been proven equal (100% comparable).

"Person A and Person B are 90% the same"

This is therefore a statement which might not make sense out of context, but with the reasoning I have just explained above, is a correct statement (according to the "compared aspect" logic).

Finally, and most importantly, if you want to hint that someone could be the same person (physically), but you are in fact uncertain at the point of making the statement, using dieselbe Person will avoid confusion, as a different form of "diesselbe Person", ein und dieselbe Person literally has the exact same meaning, but is not ambiguous at all.

Hence, I would back your first instinct, and to avoid confusion, go with "dieselbe Person."

Answer 2

In the context of databases there can (obviously?) be a difference between derselben and der gleichen person.

Consider these two entries

Max Mustermann, Musterstraße 1, 12345 Musterstadt, born 1980-01-01, height 182 cm, blond hair

Max Mustermann, Musterstraße 1, 12345 Musterstadt, born 1980-01-01, height 192 cm, dark hair

We can easily tell that these two are not the same (as in dieselbe) person, because of the height and hair color difference. Typically, you wouldn't find information about height and hair in a database with e. g. customer records, so by chance you might have identical entries, which for your purposes would be die gleiche person, but not necessarily dieselbe.

So it depends on your context whether such a thing as zwei gleiche Personen exists, but in your case I would definitely consider differentiating between derselbe and der gleiche.

Answer 3

Vielleicht helft Dir die folgenden Beispiele:

Supermann und Clark Kent sind die selbe Person.

Alle Personen sind vor dem Gesetz gleich.

Selben, ist eine einzige Person gemeint.

Gleichen, kann man als synonym von "ähnlich" verwenden.

Die Zwillingen sind zwei Personen, die komplett gleich aussehen.

Die Zwillingen sind zwei Personen, die ähnlich aussehen.