Creating multiple custom blocks in drupal 8 ├── hello_world
│   ├── hello_world.info.yml
│   ├── hello_world.module
│   ├── hello_world.routing.yml
│   └── src
│        ├── Controller
│        │   └── HelloController.php
│        └── Plugin
│             └── Block
│                  └── HelloA.php
│                  └── HelloB.php


I have used the above file structure to create blocks in Drupal 8. Both the blocks, HelloA as well as HelloB works, but only one at a time. I see block HelloA, if I remove HelloB.php and see Block HelloB when HelloA.php   is deleted. I am trying to create multiple blocks. Please guide me. Thank you very much.
Thank you very much Shawn. 

It was the @Block annotation. I was using same id for both the blocks.

/**
  * @Block(
  *   id = "show_state",
  *   admin_label = @Translation("Show State"),
  *   category = @Translation("POP")
  * )
  */