Regression in addListenerDuplicateEventTest()

[dwrobel]

#1041 introduced regression in compilation and in addListenerDuplicateEventTest() in: a969b56#diff-e72022d6187801cd2a04db1dc7405202R59

#1112 addresses the compilation regression part (ae623f5#diff-e72022d6187801cd2a04db1dc7405202R59), although the test should be fixed once the implementation will be corrected.