If you're a seller, we may have some good news for you! We've recently changed the order in which items at the same price are sold; read on for details.
Originally, all items were sold in a round-robin format; for example, imagine a user buys 10 keys at $1.95, and there are 8 sellers at that price point -- some with many keys, and some with very few. Using the round-robin format, all 8 sellers would be guaranteed to sell one key, and 2 others would sell an additional key (if they had the stock to do so).
However, as part of a database migration some months ago, we had to make a compromise in favor of site performance and switch from a round-robin format to random ordering. While this is somewhat fine when all sellers have a similar amount of items at a pricepoint, it rapidly became unfair as one or a few sellers had many more items in stock than the others.
Today, we've switched back to a round-robin format. What this means for you as a seller is that your sales will be much more consistent and reliable if you're not the largest seller of an item. It also means undercutting is less necessary as sharing a price-point with other sellers is much more fair.