Movement generally leaves behind a gap, but there are cases where a copy is employed (i.e., doubling of the moved element). The paper examines the pattern of doubling in Cantonese in two constructions, namely, topic constructions (leftward displacement) and right dislocation (rightward displacement), with regard to the different behaviours of verbs, subjects, and objects. In this paper, I model how doubling is prohibited, required, or optional. The proposal is built on two ideas: Cyclic Linearization and Chain Reduction. In particular, I suggest that doubling results when Chain Reduction is required to be suspended, which is a last resort to avoid violation of Linearization Preservation.