From the FAQ:

If a prepared statement has a name, it is only parsed once. After that, name will re-use the prepared statement regardless of what text is.

From the wiki:

(In node-postgres, if a new prepared statement is issued with the same name as an existent prepared statement, the existent prepared statement will be replaced and no error raised.)

So, the question is... which one accurately represents node-postgres's behavior? The wiki and/or FAQ should be updated to reflect the actual behavior.