var DummyView = Backbone.View.extend({
subviews: {},
...
});
The value of the subviews
property is an object. Objects are copied by reference, therefore it instance will be shared by all DummyView instances. Just move instantion in the initialize method to create own instance for each DummyView object:
var DummyView = Backbone.View.extend({
initialize: function() {
this.subviews = {};
},
...
});