secrets displayed twice if same content and same file is sent to multiscan endpoint

[alina-tuholukova-gg]

Environment

• ggshield version: 1.14.1
• Operating system (Linux, macOS, Windows): Linux
• Operating system version: 20.04
• Python version: 3.9

Describe the bug

The secret is shown twice if exactly the same file with the same content is present in the different commits.

Steps to reproduce:

1. setup a repo, create a first commit on main branch
2. create a branch B1 from main, add file with the secret, commit
3. create a branch B2 from main, add same file with the secret (same name), commit
4. scan repo with ggshield secret scan repo .

Actual result:
1st commit

• secret
• secret

2nd commit

• secret
• secret

Expected result:

1st commit

• secret

2nd commit

• secret