Sorry, not very clear...
The standard Ventoy drive has NOTHING on partition 0 - so how can you boot from it?
https://ventoy.net/en/doc_disk_layout.html
Both the legacy and UEFI boot files are on partition 1 (2nd partition)
The Ventoy menu displays the mode it has booted in and normally the BIOS also gives you a clue too, e.g. EFI: USB Kingston (Partition 1).
The BIOS menu often numbers partitions starting from 1 though (not 0) - so don't be confused by that.
So are you saying that if you place two Windows 10 x64 ISOs onto the first partition, then UEFI64 boot to Ventoy, you can boot to the older ISO but not the newer one using the same BIOS settings?
P.S. Presumably you have formatted the first large partition as something which Windows can read (e.g. NTFS)?
The standard Ventoy drive has NOTHING on partition 0 - so how can you boot from it?
https://ventoy.net/en/doc_disk_layout.html
Both the legacy and UEFI boot files are on partition 1 (2nd partition)
The Ventoy menu displays the mode it has booted in and normally the BIOS also gives you a clue too, e.g. EFI: USB Kingston (Partition 1).
The BIOS menu often numbers partitions starting from 1 though (not 0) - so don't be confused by that.
So are you saying that if you place two Windows 10 x64 ISOs onto the first partition, then UEFI64 boot to Ventoy, you can boot to the older ISO but not the newer one using the same BIOS settings?
P.S. Presumably you have formatted the first large partition as something which Windows can read (e.g. NTFS)?