Looks like the emonhub.conf duplicate nodes issue is a recurring issue, here’s a post from 2016 Emonhub.conf duplicate node decoders after update - #24 by whitecitadel @whitecitadel suggests:
I dont think a full data partition would have caused the issue for @glyn.hudson and if I try filling the /var/log /var/tmp or /tmp partitions the script appears to work fine. Can anyone else think why this line might fail:
if ! grep "\[$var\]" $emonhub_location; then
its looking for the entry [nodeid] in the emonhub.conf file, if it cant find one it will add the node to emonhub.conf.