Lol, sorry for being officially lazy and not posting a link. mg19obsefix.esp is the esp from http://www.tesnexus.com/downloads/file.php?id=21234. The UOP contains the same script and is tagged with Scripts, so shouldn't it win the conflict? If not, I'd like to be englightened as to why.
Ok. I got it now. The scripts tag is not what you think it is.
When an NPC or object has a script (the UOP ghost anim fix, OOO's harvest containers, etc) those are assigned on the relevant record. This assignment is what is being carried forward. The scripts themselves are not affected.
What you're looking at here with this mg19 fix is an actual script that has been modified. I'd have to double check, but this is something that would be covered under the Scriptcontents tag which the UOP does NOT have and won't be getting.
Scriptcontents should be used only in very specific circumstances or what you describe will end up happening. Scripts in early loading mods overriding those in late loading mods. Since tags are not selective, ANY edited vanilla scripts will be brought forward, not just a specific one. If you're only looking to pull one specific script forward out of several in a mod, you need to make a patch for it.
Also for anyone looking at this MG19 fix, it won't be added to the UOP since it requires OBSE.