Will these boots ever be the same colour?

I bought a pair of brown boots at the weekend in a sale, they were marked down from 125 to 60 quid. They are perfect in every way except the one boot (the one that was on display under the bright shop lights) is a slightly lighter shade than the one that was in the box. You can only see the difference in natural daytime light. I was told about this problem when buying the boots by the sales istant but bought them anyway. I thought that if I put the darker one in strong daylight for a while it might eventually lighten. Does anyone know if this will happen and if both boots will ever look the same? Thanks.