Cody Kessler is easily identifiable in the No. 6 jersey the reserve quarterback has worn in his two seasons at USC.

So confusion reigned last week when Kessler played on special teams in the first half against Colorado — even running for an apparent two-point conversion — wearing No. 35, the same number worn by punter Kyle Negrete. In the second half, Kessler was back wearing No. 6.

“We change jerseys all the time with our guys,” USC Coach Lane Kiffin said Tuesday. “We’ll change some more this week. Everything’s within college rules.”

It is legal for players to wear the same number so long as they are not on the field at the same time. USC’s roster includes 28 sets of double numbers, including quarterback Matt Barkley and safety T.J. McDonald, who both wear No. 7.

Kessler used to be the only player listed on the Trojans’ roster wearing No. 6 — and still is on the USC football website. However, in the school’s news release advancing the last four games, freshman kicker Alex Wood also has been listed as No. 6 on the roster.

USC routinely shuffles numbers between games for a variety of reasons. But, according to NCAA rules, “Numbers shall not be changed during the game to deceive opponents.” If cited, the infraction calls for a 15-yard unsportsmanlike conduct penalty.

However, officials typically monitor only the numbers worn by offensive linemen, which in college must be between 50 and 79.

Asked if Kessler’s number switch during the Colorado game was meant to deceive, Kiffin said, “We’re just playing within the rules of college football.”

The NCAA football rule book includes a section called the “The Football Code” which is part of the American Football Coaches Assn.'s Code of Ethics. In a list of “unethical practices,” the first item is “Changing numbers during the game to deceive the opponent.”

So was Kessler’s switch ethical?

Lawrence Wenner, professor of Communication and Ethics at Loyola Marymount University, said switching numbers “doesn’t meet the litmus test” for ethical behavior.

“To say there is no intent to deceive seems a little disingenuous,” he said, adding, “Clearly it’s going to fool some of the [opposing] assistant coaches trying to scout the personnel.”

Indeed, Kessler’s run for the two-point conversion, though nullified by a holding penalty, was certain to draw the attention of coaches from Arizona, Oregon and other upcoming USC opponents.

It was not the first time this season that USC special teams players have changed jerseys for gamesmanship purposes.

Wood, the freshman kicker, was listed as No. 39 to start the season. Then, in the week leading up to the Stanford game, USC’s news release listed him as No. 6. But before the game, with kicker Andre Heidari absent after knee surgery, Wood said special teams coach John Baxter instructed him to switch to Heidari’s No. 48.

Kessler said it was also Baxter who instructed him before last Saturday’s game to don No. 35 for the first half.

“Coach Baxter told me to put it on, so I was like, ‘All right. Yes sir,’ ” said Kessler, adding that he was “trying to look big” like the more burly Negrete. "[Tailback] D.J. Morgan came up to me and said, ‘Yeah, you look like a running back.’ ”

USC makes Baxter available to the media only on Wednesdays. A USC spokesman said Baxter declined a request to be interviewed Tuesday.

Against Colorado, USC also had receiver Marqise Lee attempt a two-point conversion run out of the wildcat formation for the first time.

Although the plays failed, they achieved their aim of giving future opponents something to think about.

“That’s a huge part of it,” Kiffin said. “That’s why we do a lot of the stuff we do.

“It’s a pain to prepare for. You’ve got to waste time preparing for that instead of spending more time on offense and defense. Marqise in the wildcat; now you’ve got to have a plan for that.”

Grant Teaff, executive director of the American Football Coaches Assn., said the organization’s ethics committee meets once a year at the annual coaches convention to discuss “15 or 20" issues that have come up during the season. The AFCA can recommend review of those issues by the NCAA rules committee.

“That’s why the NCAA rule book is four inches thick,” he said.

gary.klein@latimes.com

Twitter: @latimesklein