A bug in my script i can't seem to understand why it happens, why?

in short, i made a script that lets you run when pressing shift, and lets you walk when you let go.

you are able to run when an Intvalue is more than 0, and it increases every second by 1 when not running.

However, if you press shift two times under a second, the intvalue increases by 1 TWICE every second. from my understanding , the script malfunctions and runs the same line twice.

(the main bug starts at line 30)

repeat wait() until game.Players.LocalPlayer
local running = false
local amount = game.StarterGui.run.Value.Value

local function stoprunning()
    game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 11 
end

m = game.Players.LocalPlayer:GetMouse()


m.KeyDown:connect(function(key)
    if key == "0" and running == false then 
        print("Running")
        running = true
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 22
        while running == true do
            game.StarterGui.run.Value.Value = math.clamp(game.StarterGui.run.Value.Value - 1, 0, 100)
            local amount = game.StarterGui.run.Value.Value
            print (amount)
            wait(0.1)
            if amount == 0 then
                game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 11
            end
        end

    end
end)

m.KeyUp:connect(function(key)
    if key == "0" and running == true then
        running = false
        local amount = game.StarterGui.run.Value.Value
        game.Players.LocalPlayer.Character.Humanoid.WalkSpeed = 11 
        while running == false do
            local amount = game.StarterGui.run.Value.Value
            game.StarterGui.run.Value.Value = math.clamp(game.StarterGui.run.Value.Value + 1, 0, 100)
            print(amount)
            wait(0.9)
        end
    end
end)