execute store result score random itemcount run random value 1..2
execute if score random itemcount matches 1 run data modify entity @s Offers.Recipes append value {maxUses:8,buy:{id:skeleton_skull},sell:{id:emerald,count:2}}
execute if score random itemcount matches 2 run data modify entity @s Offers.Recipes append value {maxUses:8,buy:{id:zombie_head},sell:{id:emerald,count:3}}