Collision when merging separate release PRs at the same time

When doing multi-package releases, with "separate-pull-requests": true in release config, each package has its own PR that triggers a release when merged. When you merge them at separate times, everything works fine. However, if you merge more than one of the package PRs at the same time, collision occurs causing error.

Specifically, release please tries to build the release path for both packages in each PR run, it has errors like "package1 does not match configured component: package 2", it says it's creating a release for both packages in each run, and then eventually collides with "duplicate release tag" and "Error: release-please failed: Validation Failed... Resource already exists.." for release tag name, or "Error.. Label does not exist.." for removing the PR label in the other run.

Basically release please tries to handle both releases at the same time in each run if they're merged at the same time.

#### Environment details

- OS: Amazon Linux
- Node.js version: N/A
- npm version: N/A
- `release-please` version: 17.5.2

#### Steps to reproduce

1. Set release please config to have more than 1 component with separate pull requests
2. Merge both release PRs at the same time (trigger release please to run at the same time for each component)