Bug: MD5sum File Duplicates

[berntpopp]

Description:
Fix the issue where the MD5sum file is updated with duplicate values instead of checking for and preventing duplicates. This will ensure accurate file integrity tracking.

Tasks:

• Modify the MD5sum file update process to prevent duplicate entries.
• Implement a check for existing values before appending new ones.
• Test the fix with various input files to ensure correctness.
• Document the changes made and any impact on existing workflows.