The Micromax In Note 1 seems to be a better device as it gives great specifications at a lesser price.
Processor: The Micromax In Note 1 comes with the MediaTek Helio G85 processor whereas the Xiaomi Mi A3 comes with the Qualcomm Snapdragon 665 processor.
Battery: The Micromax In Note 1 has a battery of 5000 mAh whereas the Xiaomi Mi A3 has a battery of 4030 mAh.
Check Full Comparison Micromax In Note 1 vs Xiaomi Mi A3
Yes, the Micromax IN Note 1 does support the Dual VoLTE 4G and hence, it would support Dual 4G Jio Sim.
Check more about Dual VoLTE 4G Jio Sim-
Check Full Device Specifications Micromax IN Note 1