In ר"נ the chasam sofer says that the second day of yom tov is docheh for a safek brit milah. in רנ"ג he says that that a safek brit milah does not docheh the second day of yom tov. The first was written in Mattifdorf which means it is latter than the second one written in Pressberg.
Can someone tell me about the chasam sofer's life and if this sort of reasoning is commonplace??

Interesting.

Have you seen the Pischei Teshuva SK 7 on Siman 266? He refers to both these Teshuvos.