Yes, you can.
From Generation III onward, you can stack Spikes up to three times, dealing more damage on entering Pokémon, with a maximum of 25% damage to an opponent switching in (unless it is levitating).
If Spikes are removed from the field by moves such as Rapid Spin or Defog, then all layers are removed, so you'll have to start stacking from one again.
Know that Spikes and Toxic Spikes (2 layers = Toxic Poison) are the only two entry hazards that can be stacked. Stealth Rock, Sticky Web etc. can only be used once.