I would say generally speaking yes. But of course there are some factors to consider such as the type of lighting you'll be using, it's spread or focused beam, depth of the tank, and the width and how far apart the fixtures are. But I did a similar experiment when I used to Current Satellite LED
+ fixtures over my 17 gallon tank. When those fixtures first came out, everyone would be quick to dismiss them as nothing more than a low-light fixture on most tanks. While this may be true for a single fixture, I effectively surprised a lot of folks when I doubled up on them and grew every high-light demanding plant I threw at them. And because my tank wasn't that tall, nor was it that deep, the overlapping in light coverage from the two light fixtures was pretty even and consistent. Therefore I would have to conclude I doubled or nearly doubled my PAR (assuming of course, without a PAR meter).