Forgot the most important thing but the forum wont let me edit my answer.
You need first to merge the files if you have more than one. To do this you need to run first:
copy /b/y backup_xxxxxx_xxxxxx.tzst + backup_xxxxxx_xxxxxx.tzst1 + backup_xxxxxx_xxxxxx.tzst2 + backup_xxxxxx_xxxxxx.tzstxxx...