LE uses pulse audio for BT output. It is probably possible to pair multiple BT audio devices and configure pulse to send L and R audio streams to the two different devices. However, how exactly you do this is the unknown. There is no HOWTO guide in our Wiki and nobody on staff has muh expertise in pulse audio, and you'll discover it's a complete bitch to Google for hints due to the massive number of false hits on common terms.
This but it's really not that bad,
Pair the two speakers, create a combined_sink for them in pulseaudio. Then set the volume for each channel independently.
This of course would only work for stereo audio, I'm sure funky things would happen if you wanted to play 5.1