These files come from a challenge thread about finding well-lit renders, analyzing their light setups, and doing our best to recreate it with Blender + Cycles. It's also an exercise featured in the BC4 class, "Shading and Lighting with Blender". Kent has done several of these "light matches" and is making the .blend files available here for reference purposes.
Here's a list of the available matches:
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Source Credit: "Lüfor"by Alexandre Aroul
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Source Credit: "Sci Fi Pilot" by binqi chen
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Source Credit: "Danbo in Autumn" by tomatoes
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Source Credit: "Female sculpting session 01" by Daniel Crossland
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Source Credit: "Tribal Frog" by Paul Braddock
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Source Credit: "Super Mario" by Mark Henriksen