In KNB server, metacat request two times replication if first replication failed.
This is a subset of bug 3296.
Here is the description copied from there:
A secondary bug seems to be that each of the failed documents is sent twice,
not once. (Also described below.) Thus, for each timed replication, LTER
attempts to send over 2000 documents to KNB, KNB fails to write them into its