At the very detailed level, none.
You, for example, have a heart on one side only. Or a stomach, liver etc. Your face (and everyone else's) is not perfectly symmetrical.
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bilateral
Bilateral.
Bilateral symmetry
This is referred to as bilateral symmetry, for instance the human body whose left side is more or less a mirror image of it's right side (on the exterior, that is).
Ellipses and non-square rectangles have two lines of symmetry.