A very long time ago I knit myself the Conwy socks from Knitting on the Road (still my very favorite sock pattern book). I had two skeins of Lorna's Laces Shepherd Sock. They were two different dyelots. The color difference was always noticeable but I never really cared. Gradually though something happened. One sock began to shrink a bit every time I washed it (in the machine). The other stayed the same. Over the five plus years I've been wearing and washing the socks the difference has become *ahem* quite pronounced.
Perhaps you can detect the difference?