Environment
Android >= N (which requires ContentUri instead of File Uris)

Steps to repro

1. In Dropbox for Android: Open file A with Acrobat reader
2. In Acrobat Reader: Make edits to File A, don't save the changes.
3. Switch app to Dropbox and open file B
4. Open file B with Acrobat reader
5. Return to Dropbox
6. File B's contents are replaced with File A's edited content

Expected Result
File A should be saved.

Observed Result
File B is overwritten, and File A is not saved.

Looking at the Intents and ContentProvider Queries. Here's the time line.

In Dropbox: Open file A with Adobe.

Dropbox sends and intent to Adobe (dat=content://com.dropbox.android.FileCache/filecache/353f4cac-5e9a-452f-bbcb-aa88863485d6)

07-25 12:19:06.173 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/353f4cac-5e9a-452f-bbcb-aa88863485d6 (projection = "_size")

07-25 12:21:16.613 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/353f4cac-5e9a-452f-bbcb-aa88863485d6 (projection ["displayname", "_size"])

07-25 12:22:02.462 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: openFile: uri: content://com.dropbox.android.FileCache/filecache/353f4cac-5e9a-452f-bbcb-aa88863485d6 (mode="r")

07-25 12:21:16.613 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/353f4cac-5e9a-452f-bbcb-aa88863485d6 (projection=["localrev", "lastmodified"])

In Adobe: Make Changes to the PDF file and click on the "Check"

Nothing happens!

In Dropbox: Open File B in Adobe

Dropbox sends and intent to Adobe (dat=content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f)

07-25 12:26:09.409 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f (projection = ["_size"])

07-25 12:26:56.054 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f (projection = ["displayname", "_size"])

07-25 12:27:31.901 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: openFile: uri: content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f (mode="r")

07-25 12:28:08.953 9033-9091/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: query: uri: content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f (projection=["localrev", "lastmodified"])

07-25 12:28:51.358 9033-9671/com.dropbox.android D/com.dropbox.android.provider.FileCacheProvider: openFile: uri: content://com.dropbox.android.FileCache/filecache/47d9291a-b00c-4608-a6ce-ab1e11958e0f (mode="w") <-- This is bad: Adobe is changing the newly opened file instead of the original file!

Attaching video of the repro.