Meghan Markle reportedly clashed with some of her staff over freebie designer clothes the Duchess was being sent.
Aides are said to have advised Meghan, 39, that keeping designer clothes sent by high-end fashion brands was against royal protocol.
They claimed boxes of luxury clothing were sent to Kensington Palace after it was announced she was officially dating Prince Harry.
It comes after claims that the Duchess of Sussex, pregnant with her second child, had bullied two palace staff members surfaced earlier this week.
It led to other staff sources within the Sussex household claiming they had been left “terrified” from disagreements – including one about free designer clothes.
A spokesman for Sussexes described the claims, reported in The Times, as an “attack on Meghan’s character” that had left the Duchess “saddened”.
An aide told The Sun: “As an actress it was perfectly acceptable to take freebies sent by fashion chains and designer labels.
“But Meghan had to be told it was not the done thing when you are a member of the royal family.”
In response to the bullying allegations, Meghan’s spokesman said: “The duchess is saddened by this latest attack on her character, particularly as someone who has been the target of bullying herself and is deeply committed to supporting those who have experienced pain and trauma.
“She is determined to continue her work building compassion around the world and will keep striving to set an example for doing what is right and doing what is good.”
Friends of the Duchess have also claimed she has been left “speechless” by the accusations – but claims she “knew it would get ugly”.
The friend told Bazaar.com: “I hate to say it, but find me a woman of colour in a senior position who has not been accused of being too angry, too scary, too water in the work place.
“It’s sad that it’s happening, but I’m not surprised.”
Another friend reportedly said she and Harry “knew that it would get ugly” in the run-up to the screening of their bombshell Oprah Winfrey interview special.
The interview with the revered television host is expected to lift the lid on Harry and Meghan’s short period as working royals together before they stepped down for a life in America.
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It airs for the first time in the US on Sunday and will be shown on ITV for a UK audience on Monday.
Yesterday, Buckingham Palace revealed the allegations were being investigated, with a spokesman commenting: “We are clearly very concerned about allegations in The Times following claims made by former staff of The Duke and Duchess of Sussex.
“Accordingly our HR team will look into the circumstances outlined in the article. Members of staff involved at the time, including those who have left the Household, will be invited to participate to see if lessons can be learned.
“The Royal Household has had a Dignity at Work policy in place for a number of years and does not and will not tolerate bullying or harassment in the workplace.”