Two aliases not marking the reference as reserved = no issues at all. If one alias is marked as reserved, the other one must be marked as "allow reserved", or otherwise it will fail to fill. Meaning that if you mark the second one as reserved too, then the first one would need to be marked "allow reserved". So in your Sebastian Lort example, don't mark your alias as reserved - unless you plan to edit the original Clavicus Vile alias too. I don't know about your Movarth example - that depends on how the quest in question handles the situation. If Movarth is a reference that gets enabled, while the generic vampire boss gets disabled, then it will cause issues, because you won't be able to use a disabled reference for much in your own quest. On the other hand, if "Movarth" is just a name that gets assigned to the generic vampire boss, so that the actual reference is still the same, then the alias in your own quest will still point at that reference, Movarth or not. I hope I made any sense :)