“Heidi” & “The Secret Garden”

Aren't these the same story twice told by two different people?  Having read Heidi long time before, and rereading it now, along with The Secret Garden, it made me think; what would have happened if it was in the current era? Wouldn't the writer have been sued Had Burnett read Heidi before writing The Secret Garden? What is the connection or was it a mere coincidence? Was this a common event during that time?  There were different views on Heidi itself - some said it was a true story and others said, Johanna Spyri had borrowed the story from another book written in Germany by Adam Von Rap. Not the Von Trapp family from 'The Sound of Music', that came much later to all these. 

Having just written reminisce of the two books, as I try to reflect upon them, this is what google say: 

"Heidi is a work of children's fiction published in 1881 by Swiss author Johanna Spyri, originally published in two parts as Heidi: Her Years of Wandering and Learning and Heidi: How She Used What She Learned. It is a novel about the events in the life of a 5-year-old girl in her paternal grandfather's care in the Swiss Alps. It was written as a book "for children and those who love children".

The Secret Garden is a novel by Frances Hodgson Burnett first published in book form in 1911, after serialization in The American Magazine. Set in England, it is one of Burnett's most popular novels and seen as a classic of English children's literature. Several stage and film adaptations have been made. The American edition was published by the Frederick A. Stokes Company with illustrations by Maria Louise Kirk, and the British edition by Heinemann with illustrations by Charles Heath Robinson."

What is common in both the  books ?

• Both have an orphan girl as leading ladies; Heidi and Mary. 
• Heidi was brought to her grandfather after her parents death and Mary was brought to her uncle; as they were children. 
• Both girls find joy and become healthy outdoors. 
• Both find another child who have lost their leg - Heidi meets Clara Sesemann in Frankfurt and Mary meets Colin Craven in the moors of York. 
• Both stories have Nature boys helping them Peter helps Heidi and Dickon helps Mary
• The orphan girls and the Nature boys of both books respectively help the ones on the Wheel chair  to step out of it and walk; without their family around
• Both of them does this amidst the beauty of the nature. 
• Both books have reunion of the Children with their father, wanting to surprise him. 
• Both book emphasis on belief and positive thought helping to achieve anything. 

Both these books are about Nature, Life, Passion, Self- Confidence, Love and Hope. 

Summary of both is that Positive thoughts and place can transform a person; and both books transposes us to geographic locations akin to Paradise, which we are tempted to visit. Interestingly, we can never have enough of them - the book and the places.