How to make math.random give me a different number?

I am trying to make zombies spawn in random locations (there are 4 at the moment) and they always spawn at the same place. I tried making this custom function to try to make numbers more random but it is not working.

Every time I do a new test session in studio the number changes but it always repeats the same number.

function GetRandom(Num1, Num2)
    local Nums = {}
    math.randomseed(tick())
    for i = 1,100 do
        local Math1 = math.random(Num1,Num2)
        Nums[i] = Math1
    end
    local Math2 = math.random(1,100)
    return Nums[Math2]
end

module.PrepareZombie = function(Name)
    local Zombie = Zombies[Name]:Clone()
    Zombie.Parent = ZombieFolder
    local Spawn = GetRandom(1,#Spawns:GetChildren())
    print(Spawn)
    Spawn = Spawns:GetChildren()[Spawn]
    Zombie.HumanoidRootPart.CFrame = Spawn.CFrame
    ZombieCore.Reincarnate(Zombie)
end