LOVE2D，关于跟随物体的异步移动问题

我在制作一个跟随物体的小游戏，使用Love2D框架。 但是运动的速度会随着向量的不同而发生变化，例如向前移动速度会比向上移动稍微快一点。 请问有谁能帮帮我，找出我的错误所在么？ 以下是代码：

    function love.load()
    player = love.graphics.newImage("player.png")
    local f = love.graphics.newFont(20)
    love.graphics.setFont(f)
    love.graphics.setBackgroundColor(75,75,75)
    x = 100
    y = 100
    x2 = 600
    y2 = 600
    speed = 300
    speed2 = 100
end

function love.draw()
    love.graphics.draw(player, x, y)
    love.graphics.draw(player, x2, y2)
end

function love.update(dt)
print(x, y, x2, y2)
   if love.keyboard.isDown("right") then
      x = x + (speed * dt)
   end
   if love.keyboard.isDown("left") then
      x = x - (speed * dt)
   end

   if love.keyboard.isDown("down") then
      y = y + (speed * dt)
   end
   if love.keyboard.isDown("up") then
      y = y - (speed * dt)
   end

   if x < x2 and y < y2 then
    x2 = x2 - (speed2 * dt)
    y2 = y2 - (speed2 * dt)
   end

   if x > x2 and y < y2 then
    x2 = x2 + (speed2 * dt)
    y2 = y2 - (speed2 * dt)
   end

   if x > x2 and y > y2 then
    x2 = x2 + (speed2 * dt)
    y2 = y2 + (speed2 * dt)
   end

   if x < x2 and y > y2 then
    x2 = x2 - (speed2 * dt)
    y2 = y2 + (speed2 * dt)
   end
end