Why does God so this? :)

Genesis 46:1-2(NKJV)

So Israel took his journey with all that he had, and came to Beersheba, and offered sacrifices to the God of his father Isaac. 

Then God spoke to Israel in the visions of the night, and said, “Jacob, Jacob!” And he said, “Here I am.”

God tells Jacob to change his name to Israel.  So why does God then go back and call him Jacob?  Is it just to see if we are paying attention?  Trying to keep us on our toes?

:)