Home canning salsa - seems like recipes call for too many jalapenos?

I make fresh salsa all the time, and now i have way too many tomatoes and plan to can some salsa. but the recipes seem to call for a LOT more jalapenos than I put in my fresh salsa, and i make it about the equivalent of a medium store-bought canned salsa. ** Do the jalapenos end up milder when you cook the salsa as you are canning it in a water bath? ** Or do I have extra hot jalapenos or something? (The variety is Mucho nacho, i leave them on the plant until just before they start turning red). thx so much!