When my leaderboard fills up with ten players, it doesn't update properly. How do I fix this?

This first script is inside of the leaderboard and controls the updating of the GUI.

I was testing this script below in-game (the leaderboards are based on a person's best speed run time) and I got an error in the dev console saying the double is not allowed in datastores on line 24 and 44.

local Players = game:GetService("Players")
local ServerScriptService = game:GetService("ServerScriptService")
local DataStore2 = require(ServerScriptService.DataStore2)

for i = 1,10 do
	local Sam = script.Sample:Clone()
	Sam.Name = i
	Sam.Parent = script.parent.SurfaceGui.Frame.ScrollingFrame
	Sam.UserPos.Text = "[".. tostring(i) .."]"
	Sam.Score.Text = "Nil"
	Sam.LayoutOrder = i
	script.Parent.SurfaceGui.Frame.ScrollingFrame.CanvasSize = UDim2.new(0,0,0,50*i)	
end

function UpdateGui()

	for i,v in pairs(game.Players:GetChildren()) do
		local bestTimeDataStore = DataStore2("BestTime", v)
		local Data1 = bestTimeDataStore:Get("BestTime", true)
		local Data = Data1 * 100
		print(Data)
		local Datastore = game:GetService("DataStoreService"):GetOrderedDataStore("ScoreX1",2)
		if  Data ~= 6942000 then
			Datastore:SetAsync(v.UserId,Data)
		end

	end
	local Datastore = game:GetService("DataStoreService"):GetOrderedDataStore("ScoreX1",2)
	local Pages = Datastore:GetSortedAsync(true,25)
	local Data = Pages:GetCurrentPage()
	for k,v in pairs(Data) do 
		if tonumber(v.key) >=1 then
			local Frame = script.Parent.SurfaceGui.Frame.ScrollingFrame:FindFirstChild(tostring(k))
			if Frame and Datastore:GetAsync(v.key) ~= 6942000 then
				Frame.Username.Text = game.Players:GetNameFromUserIdAsync(v.key)
				Frame.Score.Text = tostring(Datastore:GetAsync(v.key)/100 .."s")
			end			
		end
	end

end

while true do 
	UpdateGui()
	wait(2)
end

This next script is located in ServerScriptService, and it controls the DataStores as the person gets a new time. I am using DataStore2 and OrderedDataStore for this.

local Players = game:GetService("Players")
local ReplicatedStorage = game:GetService("ReplicatedStorage")
local ServerScriptService = game:GetService("ServerScriptService")


local DataStore2 = require(ServerScriptService.DataStore2)

local defaultValue = 69420

game.Players.PlayerAdded:Connect(function(plr)
	local bestTimeDataStore = DataStore2("BestTime", plr)
	
	local leaderstats = Instance.new("Folder", plr)
	leaderstats.Name = "leaderstats"
	local BestTime = Instance.new("NumberValue", leaderstats)
	BestTime.Name = "BestTime"
	BestTime.Value = 69420
	
	local function bestTimeUpdate(updatedValue)
		
		BestTime.Value = bestTimeDataStore:Get(updatedValue)
		
	end
	
	bestTimeUpdate(defaultValue)
	bestTimeDataStore:OnUpdate(bestTimeUpdate)
	
end)

game.ReplicatedStorage.SendData.OnServerEvent:Connect(function(plr, FinalTime)
	
	local bestTimeDataStore = DataStore2("BestTime", plr)
	
	if FinalTime < plr.leaderstats.BestTime.Value or plr.leaderstats.BestTime.Value == 0 then
		plr.leaderstats.BestTime.Value = FinalTime
		bestTimeDataStore:Set(FinalTime, defaultValue)		
	end
	
end)

When the leaderboard fills up with ten players, and a player who is already on the leaderboard gets a better time, their time isn't replaced. However when the leaderboard was partially empty, the score was updating as normal, but there were sometimes two scores for the same player.

In conclusion, I would like some clarification and tips on how it would be possible to remove these errors and make sure the leaderboard updates properly (e.g. one person gets a better time than others, his time gets put in, and others times are shifted down).