Repetition repeats wording or meaning for emphasis, alertness or intensification. Clarification after ambiguity first presents a general conception and then resolves it with specific detail.
«حَضَرَ الضُّيُوفُ، حَضَرَ الضُّيُوفُ»
The guests have arrived—the guests have arrived.
«حَضَرَ الضُّيُوفُ: مُعَلِّمُونَ وَطُلَّابٌ»
The guests arrived: teachers and students.
The first highlights reiteration; the second supplies a specification. Whether either is rhetorically effective depends on the particular audience and communicative purpose.