New XBee PRO seen as 2 different modules in XCTU

I have many new XBee PRO 900HP that when discovered with XCTU (version 6.3.1) they appear as 2 different remote radios with completely different MAC addresses.
Note: Only the base station (plugged on PC with USB cable) and a new module are ON during the discovery process.

-If I change the Network Identifier of the 1st remote module the 2nd module’s NI stay to its default NI “”.

-If I change their Network ID from the default 7FFF to something else and start over the discovery process with XCTU only 1 remote module is seen.

What am I missing?

Thanks

Have you changed the ID on each radio to the new value via its serial port?

I’ve change my base station ID to 7FFF in order to communicate with a brand new remote radio.
Then when I discovered it XCTU showed 2 different remotes.
I was then able to change their NI independently like is there were 2 physical units.
I can confirm that there is no other radio ON while this was observed.

Then I changed the ID of both the base and the remote to something different than 7FFF and XCTU discovered only one remote!
I changed again the NI to 7FFF and XCTU discovered 2 remotes as previously observed.

This situation was also observed with other brand new modules (XBee Pro 900HP).

Independantly of the powered remote radio, the phantom radio has always the same SL address: 40DCE394 which has the same NI that I had changed at the beginning.
This address is not the address of one of the radio and is not the bas address.

Is it XCTU that makes this phantom module when the Network ID is 7FFF ?