Final answer:
Heraclitus believed that all things are in perpetual flux, but there is no information to confirm if he believed a twofold process accounts for all change.
Step-by-step explanation:
Heraclitus believed that all things are in perpetual flux. Becoming is the basis for all that is real. Being is unreal. All is changing. Permanence is an illusion. All things are one and one-in-many. That which is the essence of all is FIRE. The logos is the universal principle of reason through which there is a law like process in the universe that provides its existence and order.
From the given information, it does not explicitly state whether Heraclitus believed that a twofold process, rarefaction and condensation, accounts for all change. Therefore, we cannot say for certain if the statement is true or false according to Heraclitus' beliefs.