See this forum post

import esp32
from machine import Pin

r = esp32.RMT(0, pin=Pin(27), clock_div=80)
r.loop(1)
r.write_pulses((100, 100, 10, 10), start=0) 

The waveform shows alternate cycles of 100/100μs one correctly followed by a 10/10μs pulse, the other missing this pulse. The value of start does not affect this behaviour.

Tested on the reference board, firmware MicroPython v1.12-211-g9c07c973c on 2020-03-03; ESP32 module with ESP32.