Missing updateFile with isDownloadingCompleted=true when downloading duplicate documents

[grittygear4937]

Description

When downloading two documents that have identical content (same name, size, and bytes) but different remote file IDs, the second file never receives an updateFile with is_downloading_completed=true. However, calling getFile shows the file is actually downloaded.

Steps to reproduce

1. Have two messages with documents that have identical content but were uploaded separately (different remote.unique_id)
2. Call downloadFile for the first document → works correctly, receive updateFile with is_downloading_completed=true
3. Call downloadFile for the second document → never receive updateFile with is_downloading_completed=true
4. Call getFile for the second document → shows is_downloading_completed=true

Example

First file (works correctly):

updateFile: file_id=100, is_downloading_completed=true, remote.unique_id="AAA111"

Second file (broken):

updateFile: file_id=200, is_downloading_active=true, is_downloading_completed=false, remote.unique_id="BBB222"
// No further updateFile received
getFile(200): is_downloading_completed=true, remote.unique_id="AAA111"  // Note: unique_id changed after merge

there's a whole topic of how broken download notifications are

[chimruiza-collab]