Suppose you have two containers of Extremely Hallowed Shrine Powder, one with 5 uses left and one with only 1 use left. If you sell them individually the first one is worth 1200 currants or 200 favor; the other is worth 240 currants or 40 favor. If you try selling the first one and then accept the option to sell two (i.e., both) items you receive 2400 currants, not 1440. If you try selling the other one instead you will be offered 480 currants for both. If you try donating them you get the same problem - the amount of favor depends on the one you originally try donating; it doesn't take into account the fact that the other ones are partially used.