drlucky, I agree fully with you!
I’ve contact sandisk for this but they say that is not a problem.
this is a part of the email that I received form sandisk assistance:
“After reviewing the SMART attributes please be advised that these bad sectors are not affecting your SSDs and will not affect the life expectancy of your SSDs either.
If at any point you have a performance issue of any type, do not hesitate to contact us in order to proceed with a replacement of your devices if needed.”
those sectors does not affect the performances, it’s true, but affect the safety of my data and the life of the SSD.
yesterday appeared a new reallocated sector on the newest one. 
