Does Huo Wallace play two different characters in this drama? 

I don't think so, why?

it lists that he plays Gu Qing Ming  and Gu Shao Huan 

I think Shao Huan is his other name. In the past, mostly rich families gave their children  a personal name ming after their third month and another one zhi after their 20th birthday. The first one was then usually used by their closest family.

But all I know is based on a fan article. It has the explanation at the beginning.

 https://productiveprocrastination.site/2018/03/18/the-secret-behind-yi-lian-kai-yi-lian-shens-names-10-min-read/