That's the same day William and Kate are set to wrap up their tour of Ireland.
Former palace insider Dickie Arbiter said the overlap was a sign of bad communication between the two royal households.
"For the last two years they have been clashing. People are not talking to each other. We used to have communication between all the households, so there weren't clashes," he told the Times.
A senior royal source also told the Sun it would be a "nightmare" for staff.
"This sort of diary error would simply not have happened in the days before Harry decided to bail out of royal life."
"It's a nightmare as far as staff are concerned because there is no longer any control over Harry – he has nobody now working for him who has proper experience of the methods and protocol of the court system."
Harry confirmed in an ITV documentary last year that he and his brother had "good days" and "bad days".
But Arbiter said he didn't believe the diary clash was deliberate.
"I don't think it is deliberate [by Harry and Meghan]. It is a desire to do things their way, without telling anybody else what they are doing until they do it. The Ireland trip has been on for a while."
Overseas tours are, however, huge publicity events for the royal family, and Prince Charles was said to be "furious" when Prince Andrew's link to the Epstein scandal overshadowed his trip to New Zealand last year.
Their final days as Royals
The Sussexes will spend their last few days as royals at a mixed bag of events across London.
On Friday, Harry will team up with rock star Jon Bon Jovi to record a charity single to highlight the work of the Invictus Games – an international sporting event for wounded, sick or injured armed services personnel.
He'll soon be "the artist formerly known as Prince", the Livin' on a Prayer singer wryly joked this week.
The Duke and Duchess of Sussex will then present one award each at the annual Endeavour awards next Thursday.
"The Duke and Duchess will attend a pre-ceremony reception where they will meet the inspiring nominees, as well as endeavour participants and key supporters of the Endeavour Fund," a statement from Buckingham Palace confirmed.
"They will then attend the awards ceremony, where the Duke and Duchess will each present an award. The Duke will also give a short speech."
On March 7, the couple is then expected to attend the Mountbatten Festival of Music – a concert featuring the Massed Bands of Her Majesty's Royal Marines – at the Royal Albert Hall in London.
Meghan may also mark International Women's Day the following day, having last year joined a special panel of "female thought-leaders and activists" to discuss modern-day feminism and women's empowerment.
Finally on March 9, the couple are expected to join the Queen and other senior members of the royal family for the Commonwealth Service at Westminster Abbey, honouring the 53 Commonwealth countries.
That event could be the last time we see the couple in their official royal roles before they officially quit royal life on March 31.
