Would you rather rank on page 1 for one keyword at 100,000 searches per month or 10 keywords at 10,000 searches per month?
While this answer can vary based on the product niche you are in, generally speaking, it’s better to diversify your traffic given the sheer amount of competition for keywords on Amazon. That way if you lose ranking with one keyword, you are still getting traffic from the other to supplement your organic sales. If you rank for one great keyword and get pushed out by another product, your sales may suffer overall.