The fact that the holes seem to be offset from one another and in unusual locations suggest that they once fitted a home-made mount, and may have been positioned particular to that one and only mount, or drilled in seemingly at random, unfortunately. The spacing and alignment do not look like any side mount I have ever seen.
If you are looking to hide them, perhaps it is an option to fit an entirely different side mount which covers those holes so you can’t see them? Options are limited when fixing bubba’s handiwork :/
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