The commentators question the repetition of the word runt, say (,rntu wrunt). Rashi cites the Sifra which views this redundancy as a special enjoinment to the Kohanim to speak to their children. By emphasizing to their children to guard themselves from contact with any form of tumah, spiritual contaminant, they will safeguard the holiness of their families. This explanation suggests that the second “amirah,” saying, was directed towards the children. The text, however, seems to imply that each “amirah” was directed to the Kohanim.
Horav Elyakim Schlesinger, Shlita, contends that both “amiros” were intended for the Kohanim. Indeed, an important lesson in education may be inferred from this explanation. Children develop a proclivity towards the direction in which adults/parents/teachers encourage them. They follow, however, only those activities that the adults themselves practice and honor. If the parents maintain a lifestyle which is not consistent with what they want for their child, they are sending mixed messages which will have a negative effect. This is the reason for the two “amiros.” The adult is admonished to teach his children and also to act in the prescribed manner, so that his educational goals will be realized.