Heterogeneous multicore systems have been recently received much attention due to their power efficiency and ability to handle different workloads. In this paper, we consider real-time tasks with precedence constraints and fault tolerance requirements, and investigate how they can be implemented on heterogeneous dual-core systems in energy-aware fashion. Our framework is able to tolerate one transient fault per task, and one permanent processing core fault simultaneously. We develop a number of task partitioning, ordering, and frequency assignment techniques for energy efficiency. Our experimental results indicate that the proposed techniques significantly reduce energy consumption while satisfying the fault tolerance requirements.