Make use of unique prompts for paraphrasing

evoprompt/optimization.py

@@ -150,7 +150,10 @@ class PromptOptimization:
         self.save_snapshot()
 
         paraphrases, paraphrase_usage = paraphrase_prompts(
-            self.evolution_model, self.task.base_prompt, n=num_initial_prompts - 1
+            self.evolution_model,
+            self.task.base_prompt,
+            n=num_initial_prompts - 1,
+            unique_paraphrases=True,
         )
         self.total_evolution_usage += paraphrase_usage
         logger.info("Paraphrased prompt '%s': %s.", self.task.base_prompt.replace("\r", "\\r").replace("\n", "\\n"), paraphrases)