Yeah I know...I did this exact same shot just 3 days ago. The reason for the duplication stems from getting a piece of silver reflective paper at Michael's craft store and wanted to see how it would work. Decided to see how the rocks look in comparison. The shot from 3 days ago the rocks was on a piece of clear acetate on glossy black paper.
Not much of a difference that I can tell...maybe a bit more rock in the reflection due to the reflective nature of the silver (almost like a mirror) paper.