Erythema multiforme: This condition is characterized by targetoid macules with dark red centers, which matches the description provided. The symmetric distribution on the dorsal and plantar aspects of the feet also supports this diagnosis.

Fixed drug eruption: This condition can cause sharply demarcated, circular lesions that can appear on the feet. While the lesions may not always be symmetric, the description of dark red centers is consistent with fixed drug eruption.
Contact dermatitis: Allergic or irritant contact dermatitis can cause symmetric lesions on the feet, especially if the individual has been exposed to an allergen or irritant that comes into contact with both feet.
Dyshidrotic eczema: This condition causes small, itchy blisters on the hands and feet, which can sometimes appear as symmetric, sharply demarcated lesions.

Meningococcemia: This is a life-threatening condition that can cause a petechial or purpuric rash, which may appear as dark red centers on the skin. Although the rash is not typically targetoid, the potential severity of meningococcemia makes it essential to consider in the differential diagnosis.
Rocky Mountain spotted fever: This tick-borne illness can cause a rash that starts as small, flat, pink, non-itchy spots (macules) and can progress to a more severe, petechial rash. The rash can appear on the feet and may be symmetric.

Leukocytoclastic vasculitis: This condition is a form of small vessel vasculitis that can cause palpable purpura, which may appear as dark red centers on the skin. While it is a rare condition, it can cause symmetric lesions on the feet.
Sweet syndrome: Also known as acute febrile neutrophilic dermatosis, this condition can cause tender, erythematous, well-demarcated papules and plaques that can appear on the feet. The lesions may be symmetric, but the condition is rare and typically associated with systemic symptoms such as fever and arthralgias.