ROBLOX Multiple Dev Products acting very strange to me

Question

local MarketService=game:GetService("MarketplaceService")
local ProductId=1504714840
local Player=game:GetService("Players")
local Coil=game.ReplicatedStorage.SpeedCoil
local function processReceipt(receiptInfo, player)
    local players=Player:GetPlayerByUserId(receiptInfo.PlayerId)
    if not players then
        return Enum.ProductPurchaseDecision.NotProcessedYet
    end
    
    if receiptInfo.ProductId==ProductId then
    if players then
        local char=game.Workspace:FindFirstChild(players.Name)
        Coil.Parent=char
        end
    end
    return Enum.ProductPurchaseDecision.PurchaseGranted
end

MarketService.ProcessReceipt=processReceipt

local MarketService=game:GetService("MarketplaceService")
local ProductId2=1504717907
local Players=game:GetService("Players")
local JumpCoil=game.ReplicatedStorage.JumpCoil

local function processReceipt2(receiptInfo2, player)
    local player=Players:GetPlayerByUserId(receiptInfo2.PlayerId)
    
    if not player then
        return Enum.ProductPurchaseDecision.NotProcessedYet
    end
    
    if receiptInfo2.ProductId==ProductId2 then
        if player then
            local char = game.Workspace:FindFirstChild(player.Name)
            JumpCoil.Parent=char            
        end
    end
    return Enum.ProductPurchaseDecision.PurchaseGranted
end

MarketService.ProcessReceipt=processReceipt2

I tried everything changing names of parameters but still not working. I expect it to run perfectly, two dev products. Two codes above are the two codes for my two dev products for my beginner game. I've read you can't use "MarketService.ProcessReceipt" twice but after looking into the dev api I don't understand why, I'm confused.

Answer 1

As you read already, the documentation says you should set the ProcessReceipt callback only once in a single Script.

If you're selling multiple products in your experience, this callback should handle receipts for all of them.

When you set the callback a second time, it overwrites the first callback. It does not add a second callback.

So try to join your two callbacks into one :

local MarketService = game:GetService("MarketplaceService")
local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")


local ProductHandlers = {
    -- Coil
    [1504714840] = function(player)
        local Coil = ReplicatedStorage.SpeedCoil:Clone()
        local char = player.Character or player.CharacterAdded:Wait()
        Coil.Parent = char
    end,

    -- Jump Coil
    [1504717907] = function(player)
        local JumpCoil = ReplicatedStorage.JumpCoil:Clone()
        local char = player.Character or player.CharacterAdded:Wait()
        JumpCoil.Parent = char  
    end,

    -- add more product handlers here ...
}



local function processReceipt(receiptInfo)
    -- escape if the player has left before we grant the product 
    local player = Players:GetPlayerByUserId(receiptInfo.PlayerId)
    if not player then
        return Enum.ProductPurchaseDecision.NotProcessedYet
    end
    
    -- throw an error if we are selling a product we don't have a handler for
    local handler = ProductHandlers[receiptInfo.ProductId]
    if not handler then
        error("No handler exists for " .. tostring(receiptInfo.ProductId))
    end

    -- do the thing that gives the product 
    handler(player)

    -- mark this product as granted
    return Enum.ProductPurchaseDecision.PurchaseGranted
end

MarketService.ProcessReceipt = processReceipt