Yes, it's possible to attack own village, also many times that is really importand and needed way to do some stuffs.
When this is needed:
- When you want to move Artifact or WW building plan.
- Don't have enough traders and many times faster way to get crop or other resources from own or friendly villages.
- Want to capture own village so you have free slot for creating new village from off village.
- Looks funny, but many times enemy sent reinforcements and good way to kill them, specially when you capture some village and defense is coming from enemy ally.
What you will not get:
- Attacker points (if you kill own troops)
- Defense points (if you kill own attacking troops)
- Robbering points (if you steal resources)
What need to check:
- To check once again that there is no yours troops,
- To send enough troops that Residence/Palace, Wall and other default defense building don't kill some of your attacking troops. So there is no point if you are at a loss after attack.