be two sides of the same coin idiom (also be different/opposite sides of the same coin)
一枚硬币的两面；一个问题的两个方面
If two things are two sides of the same coin, they are very closely related although they seem different.
Violent behaviour and deep insecurity are often two sides of the same coin. 暴力行为和深层次不安全感，常常是一个问题的两个方面。