I don’t believe in being a pig when it comes to fuel. However, worrying about saving 20 or 30 Kg of fuel on taxi in? Next to flight crews, fuel is the cheapest commodity that goes into a jet now-a-days. What is the prestigious award does your company gives you for counting the fuel molecules that go into your motors?
You have much better symmetrical and safe control of the aircraft when you taxi in on both motors… especially on slippery surfaces. Think safety first before economy.