Duplicate iMessage Encryption/Signing Keys in Keychain

Has anyone noticed this unusual behaviour, I'm seeing multiple iMessage Encryption/Signing Keys for Public and Private. Appears each time I restart or login one extra of each is generated - if I delete all, when first restarting two of each appear, thereafter its back to one of each again.

Would have thought if new Keys are generated on restart then old should be removed automatically, but mine seem to be "multiplying" and if left unchecked take over Keychains.

I have always used Keychains to store Secure Notes so this unusual behaviour is very noticeable and wonder if anyone else has seen this and more importantly how it's resolved.