how can I synchronize 2 collections?

[guironne]

I must define 2 backend?

var backend = backboneio.createBackend();
backend.use(backboneio.middleware.memoryStore());
backboneio.listen(app, { mybackend: backend });

var backend2 = backboneio.createBackend();
backend2.use(backboneio.middleware.memoryStore());
backboneio.listen(app, { mybackend2: backend2 });

[Scott Nelson]

Client-side collections can be synchronized by sharing the same server-side backend.