Lowering of pressure

If I understand you correctly, you have 2 fuel gas streams at different pressures that you want to feed a pilot gas system.

Just install the regulators. If you think about the hydraulics (the pilots are just another downstream orifice in reality), you'll realize while it's theoretically possible (but not practical), it will be a nightmare to size for the various cases. You will waste hours tryinig to come up with orifice sizes and your downstream pressure, will at the best be only close to 0.21 barg.

If you use regulators, you can have both online at the same time with one designed to operate if the other fails. It's easy, common and flexible.