All other custom sets have to flasks for Alchemist, one in each hand. The Convicts' Trophies set's Flask of the Convicts has only one bottle in Alchemist's left hand.

Here is a comparison between this and all other sets.

Only the default set has a minor issue, where it only shows one flask in the loadout. It does have 2 flasks ingame though. All custom sets but The Convicts Trophies have 2 flasks in the loadout and ingame.