I didn't notice the symbol on the Shadow Temple's pedestal until FO mentioned it in a post on this forum somewhere about a couple of years ago. But what I didn't notice until I read the article was the symbol on the Temple of Time's warp pedestal being the same as the symbol on the Light Medallion. And technically, you do get the Light Arrows at the Temple of Time. So, it really does seem like the Temple of Time had its beginnings as the Light Temple, but was eventually repurposed.