I would like to comment that "there is a discrepancy between the Javascript JSON parser (used in validation scripts) and the one used internally by CouchDB [...] For a given key, the Erlang parser will store both values, but the Javascript parser will only store the last one" should probably read "the Erland parser is wrong".

I'm not saying what javascript does is smart, or the right way, or anything like that, but JSON is defined specifically as "a subset of Javascript", as such I find it normal to expect that javascript rules applies.

Of course, one could argue that a key being defined twice is undefined behavior (is it ? I admit to not reading the javascript specs) and thus "what the js implementations actually do" isn't a reference.