Bug: Bulk download overwrites files with the same filename

[neuralnut]

When downloading multiple files in bulk that share the same filename, Unigram overwrites previously downloaded files. Only the last downloaded file remains, causing data loss.

Steps to Reproduce

1. Open any chat containing multiple files with the same filename (e.g., multiple document.pdf files).
2. Auto download/multiple download files at once.
3. Observe the download directory.

Expected Behavior

Each file should be saved without overwriting existing files.
The app should automatically:

• Append a counter (e.g., image (1).jpg, image (2).jpg), or
• Use unique identifiers (message ID, timestamp, sender ID), or
• Preserve Telegram’s internal unique file naming logic.

Environment tested

App: Unigram 11.8 x64
Platform: Windows
Download mode: Auto

File types tested: documents (all in files in chat)