Sliding and meleeing and releasing the slide-button mid-melee allows you to chain multiple melees.

Specifically:

1. I slide towards a Recon in cover.
2. I melee while sliding.
3. I release the slide button.
4. I melee again.
5. I snap to cover.
6. I melee again.

Pretty sure this is not intended. Any state change between cover and sliding appears to reset the melee cooldown, resulting in sometimes fantastic 200+ damage melee hits. I'll get some footage of it today, but it is brutally hard to demonstrate, and you can only do a double chain if the target isn't in cover.