The standard I2CDevice class is not built to be instantiated more than once (consider it as I2CBus instead - and there is only one bus, right). Our drivers (QMatrix, Realtimeclock, TMP100, ...) internally use our class I2CDevice2 where we have implemented an automatic singleton pattern to allow "parallel" access to more than one I2C device. See the MultiI2cDeviceTest in our SDK for details and a sample.