Both texts are equally authentic.

两种文本具有同等效力。

《新英汉大辞典》

Both language versions shall be equally authentic.

两种文本具有同等效力。

youdao

This contract is made out in Chinese and English, both versions being equally authentic.

本合同以中文及英文两种文字书就，两种文字的条款具有同等效力。

youdao

In its seven seasons, Bourdain has traveled to almost every corner of the globe in search of authentic cuisine, and equally-authentic cultural experiences.

FORBES: Bad Boys Die Early, Curmudgeons Get to Age

These days, authentic stone basins are scarcer than bustles, so trough- planting zealots have taken to making their own equally porous (and much lighter) containers out of hypertufa a mixture of portland cement, peat moss, perlite and fibermesh.

WSJ: Trough Gardening: A Challenger to the Terrarium Craze?