The recorded birth date is 12 Dec 1919. The name is correct, his parents are correct. I'm sure that this is the correct person.
You don't give very much information, but apparently Ingvald and Elisa divorced and both remarried. The grave picture that Harald posted showed that Ingvald was remarried to a woman named Lena.
This grave shows that Elisa Olava (mother of Lars Anfin) remarried to a man named Ola Severin Hansen and took Hansen as her last name. Note that the birth date is exactly correct for Elisa Olava Ivarsdatter.
The cemetery records list Lars here also, and show his date of birth as 11 Dec 1919. Possibly it was just an error when it was recorded as 12 Dec 1919.http://www.disnorge.no/gravminner/bilde.php?id=122179
(Double click for the grave of Elisa Olava).
I can assure you that all the info I have given you is correct - and I don't have my "wires crossed".