The algorithm outputs more patterns that it is needed.
I have tested Mahout's PFP-Growth algorithm with the http://www.borgelt.net/fpgrowth.html FP-Growth implementation. This implementation has an option to generate closed patterns too.
When I filtered out the sub patterns from the output of Parallel FP-Growth I arrived to the same result, as in http://www.borgelt.net/fpgrowth.html
Succinctly, you are not outputting closed items
I am attaching the dummy DB along with the output of both algorithms