Particle Extrude process removes particles that has same IDs with other particle system.
Useful when two particles systems are used for a single simulation data.
For example, two set of data for large DT and small DT can be used for the log of simulation with wide variety of timescale.
(e.g. A gas cloud within which most particles float slowly, while very small number of particles collapse to clumps that evolve very fast.)