Why is the datastore save flipping values?

The time I first went on, I had 50 iron, and 2 gold. The next time, now I have 50 iron and 2 tin. The gold somewhat changed to tin, and I can't find the problem whatsoever.

This is what i'm talking about here Look at this: LINK The location of those is at ReplicatedStorage, if it helps.

SCRIPT BELOW

local DSService = game:GetService('DataStoreService'):GetDataStore('stpre')
local Items = game.ReplicatedStorage.CONFIG.Materials:GetChildren()
game.Players.PlayerAdded:connect(function(plr)

    local key = 'id'..plr.userId

    local savedvalues = DSService:GetAsync(key)

    local main = Instance.new('Model', plr)
    main.Name = 'inventory'
    local inv = Instance.new('Model', main)
    inv.Name = 'materials'
    local wepinv = Instance.new('Model', main)
    wepinv.Name = 'weapons'
    local utils = Instance.new('Model', main)
    utils.Name = 'utilities'

    for _,v in pairs(Items) do
        local ins = Instance.new('IntValue', inv)
        ins.Name = v.ItemName.Value
    end 

    if savedvalues then
        for _,v in pairs(Items) do
            for _,vv in pairs(inv:GetChildren()) do
                if vv.Name == v.ItemName.Value then
                    vv.Value = savedvalues[v.ID.Value]
                end
            end
        end
    else
        local vts = {}
        for _, v in pairs(Items) do
            for _, vv in pairs(inv:GetChildren()) do
                if vv.Name == v.ItemName.Value then
                    table.insert(vts,vv.Value)
                end
            end
        end
        DSService:SetAsync(key, vts)
    end
end)

game.Players.PlayerRemoving:connect(function(plr)
    local key = 'id'..plr.userId
    local items = plr.inventory.materials
    local vts = {}
    for _, v in pairs(Items) do
        for _, vv in pairs(items:GetChildren()) do
            if vv.Name == v.ItemName.Value then
                table.insert(vts,vv.Value)
            end
        end
    end
    DSService:SetAsync(key, vts)
end)