Parts were cloned too many times?

I have problem with cloning beacuse when script is executing it clones 3 or 2 block's in same place more than it's schould

~~~~~~~~~~~~~~~

    while true do
local x = math.random(0,3)
local pos = script.Parent.PositionOfBlocks.Value
script.Parent.PositionOfBlocks.Value = script.Parent.PositionOfBlocks.Value + 4
if x <= 2.8 then
    local grass = game.ReplicatedFirst.Generate.BlockOfGrass:Clone()
    grass.Parent = game.Workspace
    grass.Position = script.Parent.Position + Vector3.new(pos,0,0)



else
        local coal = game.ReplicatedFirst.Generate.BlockOfStone:Clone()
    coal.Parent = game.Workspace
    coal.Position = script.Parent.Position + Vector3.new(pos,0,0)

end
if (script.Parent.Name == "BasicBlock")then
 local clone = script.Parent:Clone()> 
 clone.Parent = game.Workspace
 clone.Position = script.Parent.Position + Vector3.new(0,0,pos)
 clone.PositionOfBlocks.Value = 0 
 clone.Name = ("ClonedCloner")
 end

 wait()
     end

~~~~~~~~~~~~~~~~~ No Errors :