If a stanza/key/value exists in the obfuscated config file then trying to modify it in the non-obfuscated config file is not allowed.
The same restriction applies to modifying a stanza/key/value in the non-obfuscated config file, that already exists in the obfuscated config file
Administrator response
Remove the stanza/key/value from the appropriate config file before setting a new value to the alternate config file