uhmm... that mordu beer that merida's father was talking about... was it the beer he just killed when merida was still young?? of was it different??

Mordu was the oldest outta all the three Princes from the other kingdom and he was turned into a phantom beer after he let pride, selfishness and anger get the better of him and those three elements have been keeping him alive for many years. And the beer that attacked Merida's father was just a minor character beer pretty much.

the person above me is incorrect. King Fergus literally calls the beer at the beginning Mor'Du. Mor'Du ate Fergus' leg and obviously Fergus was unable to kill him. It is the same bear. He's kept alive door magic. So to answer your question, yes, it is the same bear, but your vraag is erroneous because Fergus did not kill him.