...bosses with a 13 item loot table dropping the same two items 2-3 times in a row.
look at any lotto game in the country and show me where the same number, any number, showed up 8 weeks in a row.
Are you saying you've had an item drop 8 weeks in a row? Otherwise your 8-week quote doesn't hold up to a item NOT dropping 8 weeks in a row. If the boss drops 2 items out of 13, its very easy for a single item to not show up week after week. Some people are lucky, some people are cursed, and some items are meant to be rare.