Looks like no one has dealt with those clones I guess. Even though the clone is VERY similar, I don't know if I'd spend a few bills to take the chance. It could be great, or it could be crap...
I have seen that company and they might have copied the Mastech power supplies pretty good or they are the place that builds the Mastech unit and decided to do their own brand as well. I have the schematics for the Mastech HY5020 somewhere in my datasheets folder.