It is stated that if one’s birthday Nakshatra (Star) occurs twice in a month and prevails for more than 12 Nazhigais (approx. 4 hours 48 mins), the birthday can be celebrated on the second occurrence, provided that day is free from Sankaramana and other Doshas. I request an explanation of what “Sankaramana, etc., Doshas” means. 

When a Nakshatra occurs twice in a month, sometimes either the first or the second occurrence may coincide with the beginning of a new month (Masapirappu) or a day designated for Tarpanam. This coincidence constitutes Sankaramana Dosha. If it falls on a day when Tarpanam is to be performed, the birthday should not be celebrated on that day. For example, if an eclipse (Grahana) occurs on one of the two days, then one should celebrate the birthday on the Nakshatra day that is free from the eclipse.