You can see that both the toggle and duplex devices extend slightly beyond the electrical box's edges when installed. In order for the device tabs to not overlap, these electrical boxes are spaced 3/16" apart.
Because of the close proximity of these boxes, standard covers won't fit. But, as you can see, there is enough room for a short toggle plate and a short outlet cover.
Note that because short plates only reach the edge of the handy box, a portion of the device tabs will be exposed between the 2 cover plates.
If the electrical boxes are spaced 1/4" part, you can use 1 short plate and 1 standard plate, which may cover the exposed device tabs.