(a.) Having the opposite surfaces alike.

Janus-like Machiavellian adaptable adjustable all-around ambidexter ambidextral amphibious artful bifacial bifold biform bilateral binary binate biparous bivalent conduplicate crafty crooked cunning deceitful dextrosinistral dishonest disomatous double double-dealing double-faced double-minded double-tongued doublehearted dual duple duplex duplicate duplicitous faithless FALSE false-principled falsehearted flexible geminate geminated generally capable hypocritical left-handed many-sided mobile perfidious resourceful second secondary shifty sinistrodextral slippery supple treacherous tricky twin twinned two-faced two-handed two-level two-ply two-sided two-story twofold versatile