Don't assume what I might have done or what I might have seen. I did not change or delete any files in 1.x and I will repeat that the prompt to uninstall 1.x did not appear anywhere in the installer.
I haven't "assumed" anything, but based my reply on your report that you haven't been prompted to uninstall 1.x so, if I made an assumption, is that your report of not having being prompted to uninstall 1.x is accurate.
Since it's absolutely and totally certain the 2.x installer WILL prompt you to Uninstall 1.x first, otherwise it won't proceed, and you now have 2 O'Hare entries in the Control Panel, the only possible explanation left, is that files from the 1.x has been removed, because you haven't been prompted to remove the 1.x and you subsequently installed 2.x over it.
The 2.x installer will not check *every* single file from 1.x to decide if it's there or not. It will just check for the APPR_KORD.BGL file, to be present into the fsdreamteam\OhareX\scenery folder. If it's not there, it assumes you Uninstalled 1.x. So, it would be enough that you removed, moved or unintentionally lost that file, for the installer to assume you removed 1.x correctly. The installer correctly use that file for checking, because it's a file that was included in 1.x ONLY, but it's not supposed to be in 2.x, which means it's enough to identify an 1.x installation from a 2.x one.
Now, whether YOU removed (or MOVED) intentionally that file from 1.x, or you lost it for some reason, it's not really relevant, and won't change the fact that, the 2.x install WILL prompt you to remove 1.x, under NORMAL conditions and, under NORMAL condition, you won't have two entries for O'Hare, because the 2.x installer won't go ahead if you don't uninstall 1.x first.
You will of course have proof of this, if you just follow my previous instructions, and it will be obvious to you that, once you perform the "Reinstall O'Hare 2.x" step, after having installed 1.x, you WILL be prompted to remove it.