with the sp303 you can backup pattern, song & sample data to your pc by using a memorycard reader and simply copypasting the folder on the memory card to your pc.
with the 606 however this doesn't seem to work, it won't recognize the folder after you've copied it to your pc (and back to the memory card).

is there another way to back up your pattern and song data tot your pc ??

If your 606 is physically close enough to your PC, just connect via USB, mount the 606 as an external drive and copy folders back and forth.

You should be able to copy folders off the memory card, make sure you are following the procedure in the manual exactly. If the folder isn't in the right directory or you change the folder name the 606 won't find it.