For anyone else that hits this, the solution is to add "--force-overwrite" to the very end of the command.
After doing that, it installed fine, and works like a charm.
# opkg install onion-console-webcam --force-overwrite
Installing onion-console-webcam (0.3-1) to root...
Downloading http://repo.onion.io/omega2/packages/onion/onion-console-webcam_0.3-1_mipsel_24kc.ipk
Configuring onion-console-webcam.
