ZigBee - 2 Routers receive same network address

Hello.

I asked this at TI's forums, however you dont always get answers there.

I have two Coordinators (#1 and #2) nearby, and have several Routers trying to join to Coordinator #1's network.
Only Coordinator #1 permits Joining; Coordinator #2 doesnt permit joining.
When a Router joins Coordinator's network, its assigned with a network address.

I experience a problem where 2 Routers received the same network address 0x00-01.
This never happened when only one Coordinator was powered on, but it sometimes happens when two Coordinators are nearby.

Could you help me please figure out the source of this problem?

Thank you.

I do not know of anyone here who is using the TI Zigbee stack.