From Fedora Project Wiki

With koji-shadow, you might get something like this:

Downloading http://kojipkgs.fedoraproject.org//packages/eclipse-mdt-uml2/5.1.1/1.fc23/src/eclipse-mdt-uml2-5.1.1-1.fc23.src.rpm to /tmp/koji-shadow-KH/eclipse-mdt-uml2-5.1.1-1.fc23.src.rpm...
Uploading /tmp/koji-shadow-KH/eclipse-mdt-uml2-5.1.1-1.fc23.src.rpm...
Traceback (most recent call last):
  File "/home/karsten/koji-shadow-kh2", line 1355, in <module>
    rv = main(args)
  File "/home/karsten/koji-shadow-kh2", line 1330, in main
    tracker.scanTag(tag)
  File "/home/karsten/koji-shadow-kh2", line 849, in scanTag
    self.scanBuild(build['id'], tag=tag)
  File "/home/karsten/koji-shadow-kh2", line 783, in scanBuild
    self.importBuild(build, tag)
  File "/home/karsten/koji-shadow-kh2", line 906, in importBuild
    self._importURL(url, fname)
  File "/home/karsten/koji-shadow-kh2", line 891, in _importURL
    session.importRPM(serverdir, fn)
  File "/usr/lib/python2.6/site-packages/koji/__init__.py", line 1577, in __call__
    return self.__func(self.__name,args,opts)
  File "/usr/lib/python2.6/site-packages/koji/__init__.py", line 1939, in _callMethod
    raise err
xmlrpclib.Fault: <Fault 1: '<class \'pg.DatabaseError\'>: error \'ERROR:  duplicate key value violates unique constraint "rpminfo_unique_nvra"\n\' in \'INSERT INTO rpminfo (build_id, name, arch, buildtime, payloadhash, epoch, version, buildroot_id, release, external_repo_id, id, size) VALUES (350220, \'eclipse-mdt-uml2\', \'src\', 1444212687, \'580ffa35a3f62988331ceffe809686d7\', NULL, \'5.1.1\', NULL, \'1.fc23\', 0, 2498571, 3221262)\''>


Most likely you've tried to build a noarch package instead of importing it from primary and it failed to build. You have to manually clean up your mess now.

ppc-koji call resetBuild eclipse-mdt-uml2-5.1.1-1.fc23
ppc-koji call createEmptyBuild eclipse-mdt-uml2 5.1.1 1.fc23 NONE

Download packages from primary koji:

mkdir /tmp/eclipse-mdt-uml2
cd /tmp/eclipse-mdt-uml2
koji download-build eclipse-mdt-uml2-5.1.1-1.fc23

And now import and tag those rpms into secondary arch koji

ppc-koji import *.rpm
ppc-koji tag-pkg f23 eclipse-mdt-uml2-5.1.1-1.fc23

cd 
rm -rf /tmp/eclipse-mdt-uml2