To compare moong, masoor and toor dal, start with the same dry weight. A thicker cooked dal can contain more lentils per katori than a thin one, even when the two started with the same amount.
Compare equal dry weights
The Indian Food Composition Tables list about 24.4 g of protein for masoor dal, 23.9 g for moong dal and 21.7 g for toor dal per 100 g dry. For 30 g dry, that is about 7.3 g, 7.2 g and 6.5 g respectively. The difference between the first two is small at that serving size. ICMR-NIN, Table 1, entries B013, B010 and B021
Use your cooker to work out the difference
Weigh the dry dal you put in. Multiply the protein per 100 g by the dry amount and divide by 100. Then divide by the number of equal helpings. Count other ingredients separately if you need a fuller estimate.
Choose by the meals you make
A dal you cook regularly is a useful place to start. Try masoor for a quick meal or use the toor dal you already put in sambar. Use the cooked serving when you compare what ends up in the bowl. Compare dal water and a bowl of dal · Indian Food Composition Tables
Raw vs cooked food weight in Indian nutrition tables
One cooker example
Suppose you put 80 g of dry dal in the cooker and get four similar katoris. Each katori represents about 20 g of that dry dal. If you make it thinner next time, the protein in the whole pot does not change just because you added water. It may be spread across more helpings. Stir the pot before serving so the dal solids are more evenly shared.