Kajol was never replaced in Darr as she was never considered for the same. There were many actresses like Madhuri Dixit, Raveena Tandon and Aishwarya Rai who were considered for the same.
In fact, before Aamir Khan walked away from the project (as he requested a proper joint narration) the cast of Darr was Aamir, Sunny Deol and Divya Bharti.
When Sunny was signed he wanted Divya opposite him but Aamir insisted on Juhi Chawla. It resulted in Juhi's entry, Divya’s exit and later Aamir too made way for Shahrukh Khan.
The confusion about Kajol stems from Dil To Pagal Hai. Kajol was initially offered the role of Nisha (later played by Karisma Kapoor) but she turned down the offer.
She felt that the role was small compared to Madhuri Dixit’s lead role of Pooja. She preferred not to take a supporting or secondary character at that stage of her career.
Karisma took over the role which became a major career milestone for her. She won the National Award & Film Fare Award in the Best Supporting Actress category for her performance.
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