I found out that I have a duplicate device in my database.
The first device was seeded long time ago. It has a management address 10.251.1.1 and it is bound to a loopback interface 1.
The second device is auto discovered and has a management address of 10.99.1.1 which is bound to the loopback interface 99.
So device 1 and 2 are physical the same device but in NNMi this are 2 devices with different management IPs.
I've set up a discovery rule, that scans the 10.99.0.0/16 address range for new devices. The 10.99.1.1 address was newly configured on the device. So this might be the reason why NNMi discovered this second device. Also the loopback 99 interface is setup in the communication configuration under interface matching in NNMi.
Is it possible to stop NNMi discovering the second device again?
Thanks in advance