Why is the mouse clicking 2 guis?

Hey, I've posted this on DevForums, I'm just reposting it here bc devforums is inactive.

So, I made a guis mode for my aim training game (for mobile users) and when I click a target, it clicks the target and clicks the background (which you are not supposed to click). Can somebody possibly tell me why this is happening? I tried to increase the ZIndex for the target gui, still doesn't work. Heres the code:

game.ReplicatedStorage.OnClick.Event:Connect(function(gui)
        if started then
            totalParts += 1
            gui:Destroy()
            script.Parent.MainGui.Hit:Play()
            local x, y = math.random(1, 9), math.random(1, 9)
            print(x / 10, y / 10)
            points += 20
            accuracy += 1
            displayPoints()
            displayAccuracy()
            createNewPart(UDim2.new(x / 10, 0, y / 10, 0)) -- Creates a new gui
        end
    end)

    script.Parent.MainGui.Holder.InputEnded:Connect(function(input)
        if started then
            if input.UserInputType == Enum.UserInputType.MouseButton1 or input.UserInputType == Enum.UserInputType.Touch then
                totalParts += 1
                points -= 20
                displayPoints()
                displayAccuracy()
                script.Parent.MainGui.DidNotHit:Play()
            end

        end
    end)

Hope you can help ._.