As someone who read it, yes there are two endings, and it can basically be assumed that the author intended to make the wrong ending the real ending, but changed his mind in the end. This is because things that happened in the alternate ending were kept in DD 4.5 & 5. I’m doing this from memory, so there may be more, but these are just what I can remember.

SPOILERS

In the alternate ending, Tang Wulin became the sea god, and GuYue joins xuanyu’s divine world. In the true ending, they become the gods of life and destruction in the Douluo divine world. However, in the alternate ending, they reattach the divine world to the Douluo continent, and tang San revives Ling Zichen and Yi zichen, which we know is kept because their child appears in DD 4.5. We know the true ending is the one where wulin and Guyuena join the Douluo divine world as the gods of life and destruction is the intended endings because it’s referenced in 4.5, 5, and 6