a. In the cavity geometry we introduce, inversion on the curved mirror leads to each cavity mode having two wavelength-scale waists, and two outcoupling ports. Also annotated are the directions and transitions of the beams driving fluorescence and atom repumping. b. The conjugate imaging ports are inverted around the center of the array (red cross), indicated here for a few select pairs of ports (colored boxes) on the average fluorescence image. The black dashed box indicates the central 21 cavities which we consider for most in-depth array characterizations in the main text. c. Single-shot fluorescence images show an inversion-symmetric pattern of fluorescence due to the doubling effect (conjugate ports for which no atom has been flagged are boxed with the same color to highlight the inversion). d. The doubling is clear from the near-perfect photon correlations between conjugate ports of fluorescence spots (ordering is column-major); in Fig. 1c of the main text, the correlation is taken after imaging counts have been summed over both output ports. e. By default, this doubling effect will also induce two-atom loading, one in each wavelength-scale waist, as evidence by a tri-modal fluorescence histogram. 0-, 1-, and 2- atom loading fractions are annotated in each section. f. We intentionally lower the loading efficiency by lowering the trap depth during loading and pulsing traps on and off to quadratically suppress the double loading effect by a factor of 10× compared to the single loading probability.