Sorry if I pulled an older version of the plugin -- the source code I added was the latest version that I could find that you posted.
I am always happy to use your latest code/updates -- just send me a pull request on github when you have a fix update and I'll make sure it gets included.
I had to do failsafe reset, and now the duplicate tab has been corrected. Also, I'm still having issues regarding the plugin -> daemon.err uhttpd[1795~] : sendmail: could not send mail (account default from /etc/msmtprc
Edit: I've got some logs that might help.
Sat Oct 3 10:12:23 2015 user.err msmtp: host=smtp.domain.com tls=off auth=on user=sender@domain.com from=sender@domain.comrecipient@domain.com recipients=recipient@domain.com smtpstatus=501 smtpmsg='501 5.1.7 Bad sender address syntax' errormsg='envelope from address sender@domain.comrecipient@domain.com not accepted by the server' exitcode=EX_DATAERR
Sat Oct 3 10:12:23 2015 daemon.err uhttpd[1807]: sendmail: envelope from address sender@domain.comrecipient@domain.com not accepted by the server
Sat Oct 3 10:12:23 2015 daemon.err uhttpd[1807]: sendmail: server message: 501 5.1.7 Bad sender address syntax
Sat Oct 3 10:12:23 2015 daemon.err uhttpd[1807]: sendmail: could not send mail (account default from /etc/msmtprc)
One of the older versions worked the sendmail test with both e-mails, so, it's not a server configuration problem.