[Rag] Fix wrong usage of `num_beams` and `bos_token_id` in Rag Sequence generation (#7386)

* fix_rag_sequence

* add second bug fix

src/transformers/modeling_rag.py

@@ -882,7 +882,7 @@ class RagSequenceForGeneration(RagPreTrainedModel):
 
         hypos = []
         kwargs["num_beams"] = num_beams
-        kwargs["num_return_sequences"] = num_return_sequences
+        kwargs["num_return_sequences"] = num_beams
         kwargs["attention_mask"] = None
 
         for index in range(len(input_ids)):
@@ -916,7 +916,8 @@ class RagSequenceForGeneration(RagPreTrainedModel):
         )
 
         # bos_token_id is None for T5
-        use_bos = self.config.bos_token_id is not None and target[:, 0].eq(self.config.bos_token_id).all()
+        bos_token_id = self.config.bos_token_id or self.config.generator.bos_token_id
+        use_bos = bos_token_id is not None and target[:, 0].eq(bos_token_id).all()
 
         def _mask_pads(ll, smooth_obj):
             pad_mask = target.eq(self.config.generator.pad_token_id)