second wave of attack finds regenerated troops

I launched an attack on the camp with chuck - sector 6 - and i knocked out the dogs, the scanvengers and basically left less than half of the troops standing along with chuck.
when i had replenished my barracks, i sent another wave to sector 6 to finish off the rest of the bandit leaders camp only to find that the camp had been fully replenished with troops and chuck had regained his full health as well.
is this a bug? im not very happy that i wasted my troops like this :(
Bellexia

Bandit leaders will replenish their health after every battle if they're unbeaten.

if 2 armies are sent at the same time, after the first battle will the boss have full HP even if he does not have time to regenerate?
thank you!

Yes he will. A killed bandit stays dead, the rest will be at full strength again. This also go's for all the bosses.