When creating a tar archive with smbclient, if a share is specified and a subdirectory is specified the subdirectory is backed up and then the rest of the share is also. The expected result would be for the specified directory do be tar'ed and then the process would terminate.
For example: /usr/bin/smbclient \\\\myworkstation\\C\$ -U DOMAIN/Username -E -N -d 1 -c tarmode\ full -Tc backup.tar /Data
I would expect this to only back up the Data folder on my C$ share. Instead it backs up /Data and then proceeds to back up all the other files and folders on the root of the C$ share.
Note: I am actually using '-' in place of 'backup.tar' to collect the data returned (via backuppc)
Having Samba 3.5.4 installed, this doesn't happen to me. Can you please try if it works for you with a newer Samba version?
works also for me (using the -D parameter)