If you have two bugzilla repositories and each has a task with the same id, NB bugzilla will be unable to display the second one after it opens the first one.

Steps to see the symptom:
1) Add two bugzilla repositories A and B in NB;
2) Click the search task in repository icon on A to bring up search popup and enter an id exists in A, search the item, and open it after the result come back;
3) Click the search task in repository icon on B to bring up search popup and enter the same id which also exists in B. Ignore the item retrieved in 2 and select search online task repository. It came back but still with only one entry in the result list. If you open it, it is the one from 2).