Yes, you can dual boot using a Windows 7 Upgrade ISO.
Yes, you can dual boot using a Windows 7 Upgrade ISO.
It really doesn't. Upgrading ISO indicates you're moving to Windows 7 (must be XP, Vista or older) or transitioning from Windows 7 to Windows 8 or 10. Dual boot means running two operating systems simultaneously. Yes, you can use an upgrade ISO, but only if your current OS is compatible. No, ISO upgrades aren't meant for installing a new OS.
I see the confusion—you didn’t have time to clarify, but it seems we should focus on the issue. The text states that you can’t boot from an ISO file at all, not even a single attempt. It explains that the ISO needs to be burned onto a CD/DVD or written to a USB stick before use.
You can run two operating systems simultaneously by setting up separate partitions on your hard drive and installing each one independently. If you've upgraded an existing Windows version to a newer one, it's acceptable. You'll also require another storage partition to support the second OS for successful dual-booting.