Duplicate keys are entirely defined by the comparison function.
In the case-insensitive example above, the keys: 'KEY' and 'key'
would be considered duplicates, and assigning to the second one
-would overwirte the first. If duplicates are allowed for (with the
+would overwrite the first. If duplicates are allowed for (with the
R_DUPS flag discussed below), only a single copy of duplicate keys
is stored in the database --- so (again with example above) assigning
three values to the keys: 'KEY', 'Key', and 'key' would leave just