Another "Files cannot be appended to themselves" post

[korbelius]

Hello, I'm new in this forum and to muxing my videos.
I have two movies that I'm trying to merge. I want the video and main audio from the first one and only the secondary audio tracks from the second.
The error is, as the title suggests:

--- Errors emitted by job 'Multiplexing to file "Fight Club - Remux.mkv" in directory "F:\Fight Club 10th Anniversary Edition"' started on 2020-08-10 18:49:47 -05:00 ---
Files cannot be appended to themselves. The argument for '--append-to' was invalid.

Here is the list of tracks.

[Attachment 54486 - Click to enlarge]

I'm not sure what kind of information you would need to help ME troubleshoot this so I'll be paying attention to your comments. Thank you for your patient.

[korbelius]

Well, I found a way with "Add Files". It's weird because i tried that option before an another error occurred.