No, MacPaw is a respected Mac software developer. During this Gemini 2 review, I was personally able to locate a lot of duplicate files and didn’t run into any trouble.
Nonetheless, the amount of data you can remove depends on your usage habits and how long you have ignored the issue of duplicate files. Careful users may not have many duplicates at all, but the free version of the software allows you to check without committing to a premium license.