Here is Amazon’s description for the field Keywords in Seller Central :
“Search terms that describe your product: no repetition, no competitor brand names or ASINs.”

Say i found that buyers use these keywords (fictional example ) :

• Laptop red case
• Notebook red case

I think the answer is yes, but just to confirm with your experience … are these keywords considered as duplicate ?
“Notebook red case Laptop red case”

So keywords with no duplication should be :
“Laptop Notebook red case”

Is my comprehension right ?
thanks