Why is it said that God’s two incarnations complete the significance of the incarnation?

Bible Verses for Reference:

“So Christ was once offered to bear the sins of many; and to them that look for Him shall He appear the second time without sin to salvation” (Heb 9:28).

“In the beginning was the Word, and the Word was with God, and the Word was God” (Jhn 1:1).

Condemnation of CCP's Torture and Protection of Chinese Religious Refugees, HRWF Calls

In 2019, the CCP’s persecution of religion and faith in Mainland China has reached a peak. But it shamelessly claims that religious freedom exists in China. Ms. Lea Perekrests, deputy director of Human Rights Without Frontiers, spoke at the conference “The Long Arm of the Dragon: China’s Persecution of Believers at Home and Abroad” held in Seoul, South Korea on June 20, denouncing the CCP’s brutal suppression of The Church of Almighty God, Uyghurs and Falun Gong.