To copy a VPS, just stop it, and copy data preserving ownership and permissions, copy config, change ip, and you're done.

# OLDID=108
# NEWID=109
# vzctl stop $OLDID
# mkdir /vz/root/$NEWID
# cp /etc/vz/conf/$OLDID.conf /etc/vz/conf/$NEWID.conf
# cp -a /vz/private/$OLDID /vz/private/$NEWID
# vi /etc/vz/conf/$NEWID.conf +/IP_ADDRESS    # assign a new ip address