This is what I think you are going for, correct me if I'm off base.
I changed your 17 to be what my 17 is.
I then added 18 and 19 completely - but I dont think I edited anything else on yours.
The idea:
my 17:
When you press your 2 keys and if you are SpikesCanShootOut: Jump / wait 0.2 (so youre in the air a bit) / spawn each of your spikes (I added a set bullet angle after each spawn so they both go randomly instead of just 1) / and set to false
my 18:
Dont allow SpikesCanShoot to be true until you touch the ground again... Since it only goes off in the air now.
my 19:
If spikes arent enabled (AKA they hit the ground) - Wait a little bit then leave the game so they dont clog up space and memory.