Not sure, Clone Carnage doesn't really have an online player roster in general. While steam users can use online play, you can't find a server most the time to play on.

For now, I am under the assumption that there is no online play with GOG due to lack of mention of online multiplayer in product description and many other problems. I expect this game to never get online multiplayer.

GOG isn't popular in the mainstream and a lot of people that use gog share accounts. Also GOG being DRM-FREE makes it hard for game devs like to implement secure online multiplayer.

I can confirm that there is online multiplayer for GOG's DH:CC.

The issue is the same with Steam and Epic, there isn't a large enough player base for it.

If you and a friend have a copy you will be able to find each other.

A recommendation, join the discord for Destroy All Humans and try to schedule playtime with other people.

Feel free to add me to play as well, I will play this for hours.