Re: JunOS not identifying duplicate addresses on different interfaces of same device
At some point there was an attempt to add such check, but then it was reverted back to the original JUNOS day 1 behavior.
This is to support scenarios with 1:1 line side protection. In these scenarios customers configure identical addresses on different physical interfaces. One physical interface is active at a time (controlled by the transport equipment).
If someone needs to enforce additional checks, we have a commit script option.