With default settings, when 'putting' the file, it is clobbered without complaint or warning. When 'getting' lftp complains:

get: super.sh: file already exists and xfer:clobber is unset

I change my /etc/lftp.conf and append:

set xfer:make-backup yes
set xfer:clobber yes

When putting and getting, the files get clobbered, however no backup is made.

I've checked the settings with "set -a | grep clob" and "set -a | grep backup" and the values are correct.