Unable to edit pulseaudio config file

[Nathan Dehnel]

I made a modified config file in
/home/nathan/.config/pulse/default.pa, and then added this to
config.scm, per the manual:
https://guix.gnu.org/manual/en/html_node/Sound-Services.html

(service pulseaudio-service-type
             (pulseaudio-configuration (script-file (file-append
pulseaudio "/home/nathan/.config/pulse/default.pa"))))

But guix system reconfigure gives:

guix system: error: duplicate 'pulse' entry for /etc

How do I fix this?