How to handle duplicate nodes being added through a snippet?

[aljoshakoecher]

We need to think about the way we handle snippets which already exist.
Let's say we have this part in an existing XML document:

<person id="1">
  <name>Peter Griffin</name>
</person>

Let's assume a mapping specifies a container person[id=${?id}]] and a snippet <name>${?name}</name>. With a variable binding of ?id = 1; ?name = "Peter Griffin", we would add a duplicate name node into the person node with id 1.

Is this a good way to handle it? Or should this be skipped to not create duplicates?
I think there should be an option to configure this behavior.