He did 'repeat after me' the first time. Chief Justice Roberts bungled the Constitutional wording of the swearing in twice.
The oath (in pertinent part) is:
"that I will faithfully execute the office of president of the United States."
Roberts rearranged the order of the words, saying:
"that I will execute the office of president of the United States faithfully."
Obama began to repeat but stopped at the word"execute."
Roberts then said:
"that I will faithfully the office of president of the United States,"
leaving out "execute."
Obama then repeated:
"that I will execute the office of president of the United States faithfully."
That repeated Roberts' original mistake as to the placement of the word "faithfully."
Both Obama and Roberts had their minds elsewhere (Reggie Love and "what's a tax?", respectfully).