RFID Dual Frequency cards: embedded with 2 different chips in a single card. The combination of the chips maybe such as:
♦ Low frequency 125kHz~134.2kHz & High frequency 13.56MHz
♦ Low frequency 125kHz~134.2kHz & Ultra high frequency 860~960MHz
♦ High frequency 13.56MHz & Ultra high frequency 860~960MHz
Sometimes they are also named RFID Dual chip cards. This kind of card is produced to meet special needs of projects which work with two frequencies.