попробуйте следующее:
cd [folder_name]
for file in ./*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*/*
do
if [ -e [destination_folder]/"$file" ]; then
if [ `du -s "$file" | cut -d ' ' -f 1` -eq `du -s [destination_folder]/"$file" | cut -d ' ' -f 1` ]; then
false
else
cp "$file" [destination_folder]/"$file"...
fi
else
cp "$file" [destination_folder]/
fi
echo "$file copied"
done