Put the summary of the bug you're having here

What I expected to happen was...:
I expected the piston to move just left right quickly

What actually happened was...:
I created a redstone contraption which is a bug too.

Steps to Reproduce:
1. Put a lever down and connect a piece of redstone wire to it.
2. Put down a redstone comparater and redstone wires around it
3.Connect it with 2 sticky pistons one block above ground and put a slime block between the pistons.
4.Put down either sticky or normal piston beside the slime block.
5.Pull the lever and wait for a while,you will see duplicating pistons after a while.
The picture below is the machine I created