Small block adj. rockers

Sorry guys, I think I did a poor job of asking the question and just caused confusion. In the first pic, both shafts came from separate cars with adj. rocker set ups . The one on the left has the grooves with two holes and the one to the right just has the one offset hole. I only included the second pic. with a shaft from a standard hyd. rocker shaft, which has a single larger hole, to qualify my claim that the top shaft on the right isn't just a swapped out hyd. shaft. I was just wondering if the different adj. rocker shafts were from different years or vendors or if anyone knew why the difference?