The two birds might be ISA Browns, but could just as likely be one of a number of Red Sex Links or commercial strains of brown egg layers. The first two years are the best two years for any highly wound layer such as an RSL. Yes, they can still lay their third and fourth years, with rest, good feed and good care. Unfortunately, they can also succumb to reproductive difficulties and the like. Here's to hoping the best for you and those hens.