Neutron and Stride have not had replicated security testnets with the same chain-id as mainnet. But while Hypha administers the Cosmos Hub testnet system, this concern applies to any cosmos sdk testnet. I can’t confidently say there has never been a testnet with the chain-id neutron-1 or stride-1 so we give the warning just in case.
However, long before this feature was developed, we did host Game of Chains and had a Noble testnet called noble-1, which is the same mainnet ID that the Noble chain uses. We expect Noble to put up a proposal to join the AEZ soon, so any participants from Game of Chains need to be absolutely sure they’re not reusing a key from that chain. The easiest way to do this is simply to use a fresh set of keys for mainnet noble-1.
I want to be super clear that no one did anything wrong in the naming conventions for this testnet and mainnet chain. These decisions were all made well before cryptographic equivocation was developed. We’ll do a fresh push of comms on this specific issue if Noble joins the AEZ.
Does this only affect @serejandmyself and @pupmos? Because so far there was only one consumer chain double sign equivocation proposal on the Cosmos Hub.
These are the main concerns, yes. We’ll be talking with these validators directly. However, it’s unlikely but technically possible that there was unnoticed double-signing so again, we give the warning just in case 
You said ‘if a new key is assigned, any equivocation that occured more than 21 days ago cannot be punished’ but the double signing on Neutron of Citizen Cosmos and Pupmos happened more than 21 days ago, and in this example even if they do key reassigment today if v14 is implemented before 21 days from today they would be tombstoned? Could you clarfiy this @jtremback?
While the old key is in use or held in state, any equivocation that occurred using that key can be punished. When a new key is assigned, the old key is held in state for 21 days, during which time any equivocation using the old key can still be punished. Once 21 days pass and the old key is no longer held in state, equivocation using that key cannot be punished.
I do think the way we wrote that initial paragraph is incorrect 
@jtremback can you confirm and then @btruax, can we replace our comms paragraph with the thing I just wrote above ^