You need to use v3 listeners for this. In the end_test method you ought to be able to use something like this to create a new test:
new = test.parent.tests.create(name='New test')
new.body.create_keyword(name='Log', args=['Example'])
Or something like this to copy an existing test:
copy = test.copy(name='New name')
test.parent.tests.append(copy)
Same stuff works also with modifiers. You are working with same model objects in both cases.