We demonstrate reliable sub-nanosecond switching in two terminal STT-MRAM devices by using Double Spin-torque Magnetic Tunnel Junctions (DS-MTJs). Write-error-rate (WER) of 1E-6 was achieved in 194 devices with 250 ps write pulses and tight distributions. WER = 1E-6 was also demonstrated over a temperature range of -40°C to 85°C in a single device with 225 ps write pulses. No degradation was observed after 1E10 write cycles, written with 250 ps write pulses. We compare the DS-MTJ device switching performance to published results from state-of-the-art three terminal Spin-Orbit-Torque (SOT) MRAM devices and show a 10x reduction in switching current density (Jc) and 3-10x reduction in power consumption for devices with similar energy barriers (Eb).