Data Save is saving both values as the same when i rejoin?

It's because when you leave, you're saving the "Money" value to the same table key as the "Total" value, effectively overwriting it.

I'm not a master at datastores, but I think you could do:

local DataStore = game:GetService("DataStoreService")
local ds = DataStore:GetDataStore("CashSaveSystem")
local datas = {}

game.Players.PlayerAdded:connect(function(player)
 local data = ds:GetAsync(player.UserId) -- get the player's own datastore
 if data == nil then
  data = {Total = 0, Money = 0} -- set all data to nothing
 end
 datas[player.UserId] = data
 local leader = Instance.new("Folder",player)
 leader.Name = "leaderstats"
 local Money = Instance.new("IntValue",leader)
 Money.Name = "Money"
 Money.Value = data.Money or 0
 ds:SetAsync(data.Money, Money.Value)

 local tot = Instance.new("IntValue",leader) --remove leader.Name, you've already defined it
 tot.Name = "Total"
 tot.Value = ds:GetAsync(player.UserId) or 0
 ds:SetAsync(data.Total, tot.Value)

 Money.Changed:connect(function()
  ds:SetAsync(data.Money, Money.Value)
  datas[player.UserId].Total = tot.Value -- set the current data
 end) -- add end)?

 tot.Changed:connect(function()
  ds:SetAsync(data.Total, tot.Value)
  datas[player.UserId].Total = tot.Value -- set the current data
 end) -- remove end)?
end)


game.Players.PlayerRemoving:connect(function(player)
 local data = datas[player.UserId] -- get the player's current data
 ds:SetAsync(data.Total, player.leaderstats.Total.Value)
 ds:SetAsync(data.Money, player.leaderstats.Money.Value)
end)

I think this will work? I'm not really sure. The main thing tho is that you should have different places for different values. (You should also make it so that it only saves when the player leaves)