Most sunscreen formulas are either mineral (based on zinc) or chemical, based on various chemical filters. There are pros and cons to each type of sunscreen, and only by trying them out on your own skin can you tell which you get along best with.
If you’re among the lucky people with resistant skin, then sure, you can try combining both types of sunscreen for added protection. The sun’s rays can be so harmful if arriving on your skin unfiltered, that in this case, more is more. Add a layer of zinc lotion first, wait for it to dry, then follow up with an extra layer of long-lasting waterproof sunscreen.