No contradiction if you look into the theology, but on the outside they seem to contradict. Let’s take a look at this.
The Father generates the Son, without the Father there would be no Son. This does not at all mean the Father created the Son, the Son has always existed, but if there was no Father there would not be a Son. The Father generates the Son, in other words “begets” the Son. And the Father always existing means the Son has always been existing since the Father generates him, and that also means the Son is God since only God can be always existing.
Therefor, the Father generates (begets) the Son. The Father has existed always and because he generates the Son that means the Son has existed always (It also means the Son is God since only God has existed eternally).
Here is a good scriptural passages for God the Son’s eternal sonship.
Hebrews 13:8, "Jesus Christ is the same yesterday, today, and forever."