[Bug]: Comparison failures when trying to replace base file to a different file to compare with MD5sum

[nekohayo]

Describe the bug

Sometimes the comparison fails in confusing / unexpected ways.

Steps To Reproduce

1. wget https://freshtomato.org/downloads/freshtomato-mips/2025/2025.2/K26/freshtomato-K26MIPSR2_RT-NVRAM32K-2025.2-MiniIPv6.zip
2. Drag and drop the file into Collision
3. Click "Verify"
4. Paste 7d134c052f449a7060cd1511f73238e2 as the checksum, result is all green
5. wget https://freshtomato.org/downloads/freshtomato-mips/2025/2025.2/K26RT-N/freshtomato-RT-N66U-K26MIPSR2_RTN-USB-2025.2-AIO-64K.zip
6. Paste 82c755204d569008b818cd8027c01890 into the checksum field, it becomes red (that's kinda OK for now)
7. Click the File button (or use drag-and-drop) to select freshtomato-RT-N66U-K26MIPSR2_RTN-USB-2025.2-AIO-64K.zip as the corresponding file: it also becomes red, instead of both fields becoming green

Yet, on the commandline:

$ md5sum freshtomato*
7d134c052f449a7060cd1511f73238e2  freshtomato-K26MIPSR2_RT-NVRAM32K-2025.2-MiniIPv6.zip
82c755204d569008b818cd8027c01890  freshtomato-RT-N66U-K26MIPSR2_RTN-USB-2025.2-AIO-64K.zip

Logs and/or Screenshots

Collision.collides.with.itself.mp4

Operating System

Fedora 42

Package

Flatpak

Troubleshooting information

flatpak: true
release: true
debug: false
version: 3.10.0
crystal: 1.15.1
gtk: 4.18.4 (4.18.2)
libadwaita: 1.7.2 (1.7.0)

Additional Context

No response

[nekohayo]

Oops, I got one of the URLs wrong in the description above; edited to match.

[GeopJr]

This is essentially a UX issue that I don't know how to fix (same as #208).

The best way to explain it would be through questions. The open file is freshtomato-K26MIPSR2_RT-NVRAM32K-2025.2-MiniIPv6.zip as seen by the center title

The checksum side asks, "is 82c755204d569008b818cd8027c01890 the main file's checksum" and the answer is no ❌

The file side asks, "does freshtomato-RT-N66U-K26MIPSR2_RTN-USB-2025.2-AIO-64K.zip have the same checksum as the main file?" and the answer is no ❌

The checksum and the file tools are not connected. The app is 'per-file'; you open a file and check against it

[nekohayo]

Perhaps a way to solve this would be to have a "Replace" button next to the heading line above, and for the "File" heading to be clarified to "Compare to another file" and "Checksum" to "Compare to a checksum"?