My grandfather told me about the chocolate and sky-blue while I was still in infant school. He was born in 1899, so I'm inclined to believe what he told me. One caveat I would add, he was told that the club played its first competitive match in chocolate and sky-blue (possibly first two matches), but then switched to claret and white. As to the photos you referenced, there is no conclusive proof they were taken prior to a (competitive) ball being kicked. Personally, if people were talking about chocolate and blue during the early 1900s, it seems more than likely that it happened.
Fair enough, still not convinced.
But I wonder where did they come from and/or why we wore chocolate and blue, if we did, when the municipal colours were already identified as claret and white?