Analog Devices describes the SEPIC-Ćuk Converter. This type of DC/DC converter is used to create two outputs with the same voltage, but different polarities. This is particularly useful for powering the two rails of op-amp based circuits.
A better solution is a SEPIC-Ćuk converter. This topology consists of an unregulated Ćuk converter tied to the same switching node as a regulated SEPIC converter. This combination results in two supplies that track each other very well under all but a 100% load mismatch.