If several sellers offer at the same price, the one nearest the top of the location's character listing will win the trade. A seller with a choice among two or more buyers will pick the highest unit as it appears in the location's character listing. Since characters are added to the end of the list when they enter a location, the units who have been in a place the longest tend to appear toward the top of the list. Characters who have been in a place the longest have an advantage when one of several possible trades may be matched. However, consumption or production by the city itself will always have lowest priority.
Cities defer to characters when multiple matching trades are possible.
The location market report is ordered according to how multiple trades will resolve. A buyer would get 3682's iron, since the price is lower. A buyer would get 2019's iron. 2019 must appear before 3682 in the location character list. 1783 must come after 4846 in the location character list.