IsoMatcher can return "true" for non-isomorphic patterns.

    public static void main(String[] args) {
        Graph graph1 = SSE.parseGraph("(graph (?A :p1 ?B) (?B :p2 ?A))");
        Graph graph2 = SSE.parseGraph("(graph (?A :p1 ?B) (?A :p2 ?B))");
        IsoMatcher match = new IsoMatcher(tuplesTriples(graph1.find()), tuplesTriples(graph2.find()),
                                          new BNodeIsoWithVar(NodeUtils.sameValue));
        boolean b = match.match();
        System.out.println();
        System.out.println("IsoMatcher: "+b);
    }

            if ( n1.isVariable() && n2.isVariable() )
                return mapping.makeIsomorphic(n1, n2) ;

        graph1 = SSE.parseGraph("(graph (<_:a> :p1 <_:b>) (<_:b> :p2 <_:a>))");
        graph2 = SSE.parseGraph("(graph (<_:a> :p1 <_:b>) (<_:a> :p2 <_:b>))");