It depends on how you list them. You could make two listings, each one a lot of 4 cups. The bid price of each lot would not affect the other. Or you could list in a multiple or Dutch Auction. If you set the starting bid for each lot of 4 cups at $10 and the only 2 bids you got were $10 & $12 then each bidder would win a lot of 4 cups & each would pay $10. If the $12 bidder bid on 2 & the $10 bidder bid on only 1, the $12 bidder would get both lots, but pay only $10 for each.
In the early days of eBay there were a lot of Dutch auctions. I started buying on eBay in 1998.