Remove the deletion of property type as the instane is shared by the base model class

lib/model-builder.js

@@ -471,9 +471,11 @@ ModelBuilder.prototype.buildSchema = function(name, properties, associations) {
             var typeDef = {
                 type: type
             };
-            delete properties[p].type;
             for (var a in properties[p]) {
-                typeDef[a] = properties[p][a];
+                // Skip the type property but don't delete it Model.extend() shares same instances of the properties from the base class
+                if(a !== 'type') {
+                    typeDef[a] = properties[p][a];
+                }
             }
             properties[p] = typeDef;
         }