Except they don't Vizier. No matter how close you are forward voltage is never the same, and thermal run away will cause one diode to heavily favor the current flow vs the other unless a series resistance is used. LED's tend to be parellled in cheap flashlights, but this is at nearly their rated forward voltage and a common thing forgotten about LEDs is they have a lot of built in bulk resistance at their rated currents so in many cases the series resistors are either not needed or the device will function just long enough not to notice.