Major Description
To reproduce:
{{groovy}}
def descriptor = services.wiki.getById("xwiki");
println("Adding alias [alias1] in the descriptor for [$descriptor.id]...");
descriptor.addAlias("alias1");
println("Adding alias [alias2] in the descriptor for [$descriptor.id]...");
descriptor.addAlias("alias2");
services.wiki.saveDescriptor(descriptor);
{{/groovy}}
If you look at the wiki descriptor then, you will notice only "alias2" is configured.