I suspected as much. There are a lot of similarities between what happened to you and our own experience, which leads me to think that this may all be the work of the same person or group.
If the same 3rd party has tried to take both of our games, it is likely that we're not the only ones. My team is trying to track down and get in touch with any other affected studios. Hopefully we'll be able to put a stop to this.
The stolen version of our game has been removed from Steam, and we are taking steps to have the unauthorized content removed from other platforms as well.
Best of luck getting Death Slave taken off Steam! Happy to support your efforts if we can :)