In statements to ABC News, Thomas and Kester say that they went public with these claims to help other alleged victims and show the public that any claim against the actor, 80, isn't an "isolated one."
Hoffman's rep and lawyer did not immediately return ABC News' request for comment, but the actor's attorney sent a letter to Variety's owner, Penske Media Corp., calling the allegations in the article "defamatory falsehoods."
Kester told Variety she was a recent college graduate living in Los Angeles when the actor allegedly assaulted her at a music studio where tracks to the 1987 film “Ishtar” were being produced. She said she was dating a man who worked on the music for the movie and while she was visiting the studio, Hoffman "grabs me."
She said she was briefly in the recording booth with the actor when he stuck his hand "down my pants" and violated her with his fingers for about 15 to 20 seconds.
"And the thing I feel most bad about is I didn’t know what to do. I just stood there. I just froze in the situation like ‘Oh my God, what is happening?’" she said. "I felt like I’d been raped. There was no warning. I didn’t know he would do that.”
Thomas alleged in the Variety story that one Sunday in 1980 when she was 16, she spent an afternoon with Karina and Hoffman. After Karina left, she was waiting in the actor's hotel room for her mother to pick her up.
He came "out of the bathroom with a towel at first wrapped around him, which he dropped. He was standing there naked. I think I almost collapsed, actually," Thomas told Variety.
Hoffman then asked her to massage his feet, she said.
"What saved me was that the phone rang, and it was my mother downstairs to pick me up," Thomas said. She told Variety that she never told Karina and that they have remained good friends.
Thomas told ABC News in a statement that she decided to go public about the alleged incident after reading the account of Anna Graham Hunter, the first woman to make accusations of sexual misconduct against the actor. Hunter, in a guest column in The Hollywood Reporter last month, detailed unwanted touching from the actor.
At the time of Hunter's column, Hoffman issued a statement to The Hollywood Reporter saying, "I have the utmost respect for women and feel terrible that anything I might have done could have put her in an uncomfortable situation. I am sorry. It is not reflective of who I am." Hunter later told John Olivr that while he apologized if any of his behavior offended anyone, he did not believe that he did anything wrong.
Thomas told ABC News, "When [her] story came out on November 1. I was on a plane to San Francisco."
"When I landed, I was bombarded with texts and emails carrying the link to her story. I was shocked, as I had always believed my experience was an isolated one. I recognized Ms. Hunter’s story as the truth immediately because of the similarities to what happened to me," she said.
Thomas added, "I was so disgusted by some people implying Ms. Hunter was lying and questioning why it took her so long to come forward, when I knew without a doubt she was telling the truth, that I decided to support her and lose my preference for privacy."
Kester told ABC News in a statement that she decided to speak out "as circumstances evolved over the past weeks."
"While I felt stressed beyond belief, I also recognized that I was being given one of those rare opportunities in a lifetime, a moment where one can transcend oneself and make a difference for others," Kester said. "As with many women who have been assaulted, discussing it made me feel embarrassed, dirty somehow, and very anxious about how speaking publicly would impact my family and friends."
Kester added, "It became clear that without my going public the reporter would be unable to publish [the] stories" of other alleged victims. "They needed two women on the record. Cori Thomas had already stepped up and now it was my turn. It was my teenage daughter who gave me the last shot of courage -- 'Mom, you have to do it for the sisterhood.' So I did."