Bob's confidante went on to give an example of one of the "odd" gifts, explaining she witnessed the 82-year-old receive a shower cap on his anniversary, deeming it "really strange".
The former Australia Zoo employee also confessed that Bob and his second wife Judy did return one of the gifts, but clarified that the Crocodile Hunter's father had never received any correspondence from Bindi herself.
"To me, it's a passive aggressive thing to do," Amanda said. "That's my perspective, not Bob's, but it's strange".
This isn't the first time that Amanda has spoken out against Bindi's allegations.
Earlier in the week, Amanda told Channel Seven that Bob is "devastated to his core" at Bindi's comments.
"He has nursed me through some tough times in my life, and had my back through thick and thin," Bob's close friend said. "He is nothing but kind. To write that there is psychological abuse from the kindest, most beautiful soul I have ever met, is heartbreaking."
WATCH: Bob Irwin opens up about the death of Steve Irwin (Story continues after video)
This devastating feud was brought back into the limelight after Bindi responded to a comment questioning why she had excluded her grandfather from a Father's Day tribute.
In the since-deleted response, Bindi wrote: "I really wish that my entire family could spend time with Grace. Unfortunately, my grandfather Bob has shown no interest in spending time with me or my family."
The 22-year-old went on to claim that Bob has returned her gifts after opening them and even called his behaviour "psychological abuse".
"He has ignored me, preferring to spend time doing anything else rather than being with me," she wrote. "He has never said a single kind word to me personally. It breaks my heart."
Bob's relationship with his daughter-in-law and grandkids has been turbulent since the tragic death of his son Steve.
Just 18 months after Steve lost his life in 2006, his widow Terri had a reported falling out with Bob, prompting the Crocodile Hunter's father to leave Australia Zoo in March 2008.
The conservationist himself got extremely candid about what prompted his departure from the zoo during an episode of Australian Story.
"I just felt that it was better for everybody concerned if I left Australia Zoo and Judy and I and all our friends were able to continue Steve's work the way I believe it should be done, Bob said on the program.
"The problem I had was that the management and I didn't agree on certain aspects of Australia Zoo after Steve's passing… because most times I went into Australia Zoo, I would have a different sort of opinion with somebody… or I may have an idea and it would not be listened to."
Following all the backlash, Bindi recently announced she will be taking a break from social media to prioritise her mental health.