http://pastebin.com/a2gPaMK1

If you make a deployer place Display cases in front of block breaker it will duplicate the block and throws the above error.

As I was cleaning up my own repository, I ran across this issue (I don't remember it being reported) which references this one.

I looked at the code on my end and my question is: does the deployer count as type EntityPlayer? (I cannot find the relevant class in your repo).

Is this still a thing? This is an ancient bug report and it might have been fixed. Could somebody test it?

I'm going to close this because we haven't had news about it in a long long time but if it still happens I'll open it again.