DELETE ADJACENT DUPLICATES, delete the next row if it has the same key, so if you order first the content of the table descending. First key has the newest date and the next row has the second newer date.
sorted descending:
1000 2 fan 8/4/2013
1000 2 fan 8/3/2013
1000 1 tv 3/10/2013
1000 1 tv 3/9/2013
DELETE ADJACENT DUPLICATES:
1000 2 fan 8/4/2013
1000 1 tv 3/10/2013
Regards,
Alberto