Original Summary (Jira didn't like the long summary):

Error “InvalidOperationException: Duplicate address ‘2’ found in Addresses.” is present when building Addressables with the Scriptable Build Pipeline and Internal Asset Naming Mode set to “Dynamic” while the Asset Group is set to “Pack Separately”

Reproduction steps:
1. Open the attached project "ReproProj"
2. Open Addressables Groups (Window > Asset Management > Addressables > Groups)
3. Select “Build > New Build > Default Build Script”
4. Observe the Console

Expected result: No Errors exist, and Addressables are built
Actual result: Error “InvalidOperationException: Duplicate address '2' found in Addresses. Each address must be unique.“ is present

Reproducible with: 2.4.3 (6000.0.48f1), 2.7.0 (2022.3.65f1, 6000.0.55f1, 6000.1.14f1, 6000.2.0f1, 6000.3.0a4)

Testing environment: Windows 10 Enterprise 21H2
Not reproducible on: No other environment tested

Notes:
- This exception does not occur when the Internal Asset Naming Mode is set to anything other than Dynamic
- Reproducible when there are numerous files in the group