The included pattern "Packed Circles" uses two unnecessary circles

The included pattern "Packaged Circles" uses four circles to draw the pattern, but only two of the circles are necessary.

This is the default pattern (see the file /share/patterns/patterns.svg):
    <pattern
       inkscape:collect="always"
       patternUnits="userSpaceOnUse"
       width="1"
       height="1.73205080756"
       patternTransform="translate(0,0) scale(10,10)"
       id="Packedcircles"
       inkscape:stockid="Packed circles">
       <circle style="fill:black;stroke:none" cx="0" cy="0.5" r="0.5"/>
       <circle style="fill:black;stroke:none" cx="1" cy="0.5" r="0.5"/>
       <circle style="fill:black;stroke:none" cx="0.5" cy="1.36602540378" r="0.5"/>
       <circle style="fill:black;stroke:none" cx="0.5" cy="-0.366025403784" r="0.5"/>
    </pattern>

The following pattern produces the exact same results:
    <pattern
       inkscape:collect="always"
       patternUnits="userSpaceOnUse"
       width="1"
       height="1.73205080756"
       patternTransform="translate(0,0) scale(10,10)"
       id="Packedcircles"
       inkscape:stockid="Packed circles">
       <circle style="fill:black;stroke:none" cx="0" cy="0.5" r="0.5"/>
       <circle style="fill:black;stroke:none" cx="0.5" cy="1.36602540378" r="0.5"/>
    </pattern>

I haven't really looked into why, but it probably has to do with some symmetry operations.