Carl Ludvig Olsen 1856- 1915

I am new to this site and wondered if anyone could help me with information. Carl Ludvig was my great grandfather who either emigrated to New Zealand, or as he was a seaman, came out as crew. He was born in Oslo and I have found his family in the 1865 and 1875 censuses. His father was Herman Olsen born in Grue in 1824 and his mother Andrine Casperdr born in 1822 and married 23 October 1850. It appears Herman was married twice, the second time to Sofie Hansen. Going back the next generation has been confusing. Herman's mother Kari Olsdr was living with them in the 1875 census. I have mostly been using Family Search and Herman's mother as given at his birth is Kari Larsdr. Would these be the same and she has changed her name or have I got the wrong birth notice?. Would this be her that married Ole Hermansen in 1816 in Vinger, Hedmark.? I would also love to find out more about Andrine Caspersen, father Casper Hansen. I would really appreciate any help that I could be given.