The difference could affect how universities approach rape investigations and prevention. For example, repeat cases raise questions of whether universities should be faster to remove students from campus after accusations.

“There are repeat offenders who seek out victims and will do this time and time again with impunity because there is no punishment,” said Annie E. Clark, a co-founder of End Rape on Campus, a nonprofit organization that works to assist those who have been raped and to prevent campus sexual violence. She added, “Whatever the number is, it’s way, way too high.”

A few recent cases, and the lawsuits they have spawned — like the one at Kansas State — have again put a spotlight on repeat campus rapes, and the questions they leave about whether something could have been done. Many university administrators say they are hampered in sexual assault investigations by women who are reluctant to identify their assailants or press charges. They also say that assaults frequently occur during parties at which students were drinking, leaving their memories clouded and the truth of what happened elusive.

At Kansas State, the federal government is now involved, investigating the university’s handling of the 2014 complaint by Ms. Weckhorst. The university is facing lawsuits by Ms. Weckhorst and another Kansas State student, Tessa Farmer, who also alleges she reported a rape that was not properly investigated, as well as the case brought by Ms. Stroup, now 19, who joined Ms. Weckhorst’s lawsuit in November.

At Indiana University, a former student, John P. Enochs, pleaded guilty last year to misdemeanor battery, the result of a plea bargain. He had initially faced two counts of rape. A lawsuit filed against the university in June by one of his accusers, identified as Jane Doe 62, says Mr. Enochs raped her while she was passed out from drinking at his fraternity house. The suit says the university ignored Mr. Enochs’s history of sexual assault, failing to take steps to protect her from rape.

Nearly two years before Jane Doe 62 said she was raped, Mr. Enochs had been accused of sexual assault by another student. That woman supplied his name to university police, but initially declined to press charges.

In a statement by its spokeswoman, Margie Smith-Simmons, the university said its policy “provides for prompt response, a fair, impartial and robust investigation, and adjudication process when responding to reports of alleged sexual assault.” But, she added, “our ability to do so is also reliant on the involvement and cooperation of those who may have been harmed.”