[Substance Painter] Distorted projection issue with overlapping UV islands

So, I have the assumption (correct me if I’m mistaken) that identical UV islands (in this case, for sections that are symmetrically mirrored on the mesh), can just be stacked over each other to give them more space, which allows them to be scaled up to hold more pixels and keep the UV maps from getting too cluttered. I’m pretty sure I’ve seen this done before where it works. But in Substance Painter, this seems to result in an issue that causes this random checkered pattern to appear in the material channel. It becomes noticeable on the model itself, along with a stretched-out effect, if I have anything other than UV projection selected in the projection settings, leaving me stuck between either that or seams along the edges. Would there be any way to fix this without having to go back and do more changes to the UV maps?