Admin form saves settings twice

The function system_settings_form() will save variables into the variables table, but there is also a submit handler here that adds additional variables into the variables table (this time with properly prefixed names).

Additionally, what we're doing in the submit handler is validating, changing the values, and if the input isn't accurate, we're changing them back. Instead of doing this in the submit handler, let's add a validation handler instead, and only allow the values to be changed if they are correct.