“scratched” ,,, I have only heard that term associated with tape storage (and I was a datamanagement pro) ,, meaning that a tape dataset has been marked in the catalog (ie. the “TMC” or tape management catalog) as being available for re-use, it is a “scratch” volume ... obviously the data is still on the tape until it is reused and possibly after re-use if the data put on the volume is small... although you would need special utilities to read past the eof marker.
So what I expect happened is that they did a low level format and put it back in service. Because they don't track at the component level they don't know what machine it went to.
I expect this is coming out because "shredded" drives are probably handled by an outside company that WOULD keep track of serial numbers and would provide certification, by serial numbers, of destroyed drives.