Is to prevent the amino acid, l-dopa from beng metabolized to dopamine in other tissues in the "periphery" , that is outside the blood brain barrier. Carbidopa doesn't cross the blood brain barrier but inhibits an enzyme in peripheral tissues which deactivate l- dopa by converting it to dopamine, and since dopamine itself does not enter the brain either, along with reducing the amount of l-dopa in circulation which is available for uptake into the brain, the resulting peripheral dopamine has a negative effect on cardiovascular function.
Thus using Mucuna is like using the first prepartions of Levodopa, which contained no carbidopa, and was replaced in it's formulation, since it was shown that smaller doses of levodopa were more effective when administered along with. Carbidopa. I believe that dyskinesia are caused by a " flooding" of dopamine in the dopaminergic transpotrer in the motor control areas in the forebrain , IMHO, mucuna does not offer any real advantages, other than it is cheaper than the synthetic product. An explanation for your experience with dyskinesia from sinemet, can be found in speculating that you are overdosing on sinemet, that is, your dose is overestimated because the carbidopa is doing its job just fine. But nothing wrong with using mucuna to obtain getting PD relief, just be warned that you will probably work your way up to a larger overall dose of l- dopa, and it could result in earlier onset of dyskinesia.