Sowbagyavathy Renuka, Greetings. When the thithi falls twice in the same Tamizh month, such confusions take place. For some odd reasons, I notice Smarthas choose the earlier date while Vaishnavas choose the later date. But in the case of Karthikai pournami Deepam, everyone follows Smartha's decision.. In my area, Annamalai Deepam was the day everyone followed. Cheers!