[Bug] Compatibility issues when migrating from Dubbo 2.5.x to 3.3.x

### Pre-check

- [x] I am sure that all the content I provide is in English.

### Search before asking

- [x] I had searched in the [issues](https://github.com/apache/dubbo/issues?q=is%3Aissue) and found no similar issues.

### Apache Dubbo Component

Java SDK (apache/dubbo)

### Dubbo Version

Dubbo 3.3.5, JDK 1.8, Linux

### Steps to reproduce this issue

When migrating Dubbo2.5.x project up to 3.3.x, there are two issues found.
1. If there are two registry defined, but their properties are all same except the Id of registry. This is ok with Dubbo 2.5.x, but the project cannot start with Dubbo 3.3.x.

2. If there is dubbo:annoation in the xml config, the project cannot start with Dubbo 3.3.x

### What you expected to happen

It should be smooth during migration up to 3.3.x.

### Anything else

_No response_

### Do you have a (mini) reproduction demo?

- [ ] Yes, I have a minimal reproduction demo to help resolve this issue more effectively!

### Are you willing to submit a pull request to fix on your own?

- [x] Yes I am willing to submit a pull request on my own!

### Code of Conduct

- [x] I agree to follow this project's [Code of Conduct](https://www.apache.org/foundation/policies/conduct)

Start by reproducing the migration from a Dubbo 2.5.x project to Dubbo 3.3.5 on JDK 1.8 and Linux. Investigate startup behavior with two registries that differ only by ID and with dubbo:annotation in the XML configuration. Done means both configurations start successfully during migration, ideally with a minimal reproduction to confirm the fixes.

Written by the indexing model from the issue text.