double barrel mainspring concept from Jaeger-LeCoultre.
Double barrel power concepts generally power the gear train serially or in parallel, but the Jaeger-LeCoultre Duomètre functions somewhat differently. Rather than combining the power of two mainsprings, a Duomètre movement uses each mainspring to power a different part of the movement. For example, the JLC 380 movement in the Jaeger-LeCoultre Duomètre à Chronographe uses one barrel to power the timekeeping functions and another to operate the chronograph portion.
Although the Duomètre product line is related in concept, not all Duomètre movements share much technology