The first image shows that i am second in the queue selling 5 of the item at 12,499,991 whereas there is someone else ahead of me selling 7 of the item at the same price.
The second image shows that i have undercut by 1 ISK to sell the 5 items at 12,499,990 with the order open for 3 months.
And then the third image, which took me by surprise, shows the other seller has priced at the same price as me but is now first in the queue.
That took me by surprise because i thought someone who posts to sell at the same price comes behind the existing same priced sales.
The fourth image shows be undercutting by 1 ISK again only to see the other seller come in at the same price later on but come in front of me!
Hence, the only reason i can think of why this seller is first is because the expiry time of their order is shorter (14 days vs my 90 days)