Defensive fire oddity

[jackx]

Played the "Killing Fields" scenario today. Had trouble overrunning the leftmost Austrian battery - I managed to attack from a direction not covered by the guns to avoid canister, but to my surprise, my unit still faced 2x defensive fire.
Turns out that both the infantry units stacked with the battery were somehow eligible for defensive fire.
Oout of curiostiy, I then launched a frontal attack as well, and sure enough, that unit was then hit with 2x musketryy and 1x canister.

The battery position:



IIRC, the second infantry unit moved into the artillery hex after I'd already engaged the defenders.

First time that I've seen this happen in both FtG and PG.

Edit: Since both units are under different commands, they are also both eligible for normal first fire.