- [x] I have searched the [issues](https://github.com/apache/incubator-dubbo/issues) of this repository and believe that this is not a duplicate.
- [x] I have checked the [FAQ](https://github.com/apache/incubator-dubbo/blob/master/FAQ.md) of this repository and believe that this is not a duplicate.

### Environment

* Dubbo version: 2.7.0
* Operating System version: Windows7
* Java version: jdk8

### Steps to reproduce this issue

1. stop dubbo service
2. dubbo client set checked = true.  do get cudbbo client for times.
3. the size of list field [urls] in ReferenceConfig wil increase

Pls. provide [GitHub address] to reproduce this issue.
(project)[https://github.com/vio-lin/incubator-dubbo/tree/error-situation]  
run java file 
 incubator-dubbo\dubbo-demo\dubbo-demo-xml\dubbo-demo-xml-consumer\src\main\java\org\apache\dubbo\demo\consumer\Application.java
### Expected Result
the [urls] in ReferenceConfig will be updated.

### Actual Result
the avalidable registery urls be add to [urls] in ReferenceConfig

@SuppressWarnings("unchecked")
    public void setMethods(List<? extends MethodConfig> methods) {
        this.methods = (List<MethodConfig>) methods;
    }
    public ConsumerConfig getConsumer() {
        return consumer;
    }
    public void setConsumer(ConsumerConfig consumer) {
        ConfigManager.getInstance().addConsumer(consumer);
        this.consumer = consumer;
    }
    public String getProtocol() {
        return protocol;
    }
    public void setProtocol(String protocol) {
        this.protocol = protocol;
    }
    // 
    Invoker<?> getInvoker() {
        return invoker;
    }
    @Override
    @Parameter(excluded = true)
    public String getPrefix() {
        return DUBBO + ".reference." + interfaceName;
    }
    private void resolveFile() {
        String resolve = System.getProperty(interfaceName);
        String resolveFile = null;
        if (StringUtils.isEmpty(resolve)) {