(Isaiah 41:2:) "Who has roused up righteousness from the east, calling him to His foot?" The Holy One, blessed be He, said: Abraham illumined My world with his righteousness. Why? Because his whole generation were wicked, and out of all of them I found only one, as it is said (Ezekiel 33:24): "Abraham was one." But were there two? Rather, he was one in his righteousness. And likewise the Holy One, blessed be He, said to him (Genesis 22:11): "Abraham, Abraham." Why two times? Rather, it is that Abraham was righteous from his beginning to his end. And likewise (Genesis 46:2): "Jacob, Jacob"; and likewise (Exodus 3:4): "Moses, Moses"; and likewise (1 Samuel 3:10): "Samuel, Samuel" — they were righteous from their beginning to their end. From what do we read concerning this matter? (Genesis 6:9): "These are the generations of Noah: Noah."
Why Scripture Doubles the Names of the Righteous from Abraham to Noah
Midrash Tanchuma Buber, Noach 1:2
מי העיר ממזרח צדק יקראהו לרגלו (שם מא ב). אמר הקב"ה אברהם האיר עולמי בצדקו, למה שהיו כל דורו רשעים, ומכולם לא מצאתי אלא אחד, שנאמר אחד היה אברהם (יחזקאל לג כד), וכי שנים היו, אלא אחד בצדקו, וכן הקב"ה א"ל אברהם אברהם, למה שתי פעמים, אלא הוא אברהם צדיק מתחילתו עד סופו, וכן יעקב יעקב, וכן משה משה, וכן שמואל שמואל, צדיקים מתחילתן ועד סופן, ממה שקרינו בענין אלה תולדות נח נח.