I have tried multiple times to install Elementary os 5.1 on a win 10 machine either in "try" or "install" mode. However it boots into UBUNTU!! Do not know why this is happening
Make sure that you have downloaded the ISO from the official site and that you have created a Bootable usb key from this ISO image and not another. There should be no problem testing or installing Elementary OS.
HERE the official place for download the ISO