How can restore backup without doing Original data directory 'mysql' empty.

I added

$INNOBACKUPEXFULL --defaults-file=$MYCNF --force-non-empty-directories --copy-back $FULLBACKUP > $TMPFILE 2>&1

How can resolve below error.?

~$ sudo sh restorebackup.sh /home/…/…/data/backups/full/2016-01-03_23-55-24 /

restorebackup.sh: MySQL backup script
started: Wed Jan 13 02:52:21 PST 2016

Restore 2016-01-03_23-55-24

Preparing …

Restoring …
stop: Unknown instance:
mysql start/running, process 8092
innobackupex-1.5.1 failed:

---------- ERROR OUTPUT from innobackupex-1.5.1 ----------

InnoDB Backup Utility v1.5.1-xtrabackup; Copyright 2003, 2009 Innobase Oy
and Percona LLC and/or its affiliates 2009-2013. All Rights Reserved.

This software is published under
the GNU GENERAL PUBLIC LICENSE Version 2, June 1991.

Get the latest version of Percona XtraBackup, documentation, and help resources:
[URL]Percona XtraBackup - MySQL Database Backup Software

IMPORTANT: Please check that the copy-back run completes successfully.
At the end of a successful copy-back run innobackupex-1.5.1
prints “completed OK!”.

innobackupex-1.5.1: Starting to copy InnoDB system tablespace
innobackupex-1.5.1: in ‘/home/…/…/data/backups/full/2016-01-03_23-55-24’
innobackupex-1.5.1: back to original InnoDB data directory ‘/var/lib/mysql’
innobackupex-1.5.1: Error: Cannot overwrite file: /var/lib/mysql/ibdata1 at /usr/bin/innobackupex-1.5.1 line 2128.