Aren't split green peas just fresh green peas that have been dehydrated? If so, why after being cooked [and rehydrated] do the split peas show as having 60% more protein than cooked fresh green peas?
How are you measuring the 2 different types of peas? By volume or weight? I suspect that you might get a closer match measuring by weight -? Also, you don't know for sure that cooking (and thus rehydrating) the split peas rehydrates them to the exact same level as the fresh peas, so even if you went gram for gram, if the dried split peas had less water and thus more dry matter, you'd have more protein, more fiber, etc., I would think.
To get the best accuracy, I'd use the listing for fresh peas if that was what I ate and the listing for dried split peas if that was what I ate.