Because of consistency, an attribute can only have one preset value list otherwise it will be changed back and forth and there is no way to validate the correctness of the values.
The relevant list is defined by the connection to the feature which is inside a structure of type "Maintenance" (either primary or secondary maintenance structure), so there can only be one maintenance-connection per attribute.
Typically there is one central maintenance structure where the attributes get maintained and the output structures only get connected to those but do not specify differing values.
In your case, can't you just have 2 attributes "Sale Line Channel A" and "Sale Line Channel B" if they have conflicting value lists?
One other approach would be to investigate into the "different default value", (which is a structure-specific overwrite value for output structures) but this is available in the Desktop UI only.
You might also check into how standardized structure systems such as ETIM and eClass are managed in P360 (see Daniel's white paper). You can add indications between characters that are unlikely to be part of the actual label and strip them off on syndication.
I've used something similar to:
Safe Line [A]
Safe Line [B]
You can also do something similar with the identifiers of the features and presets.
thanks for your answer.
I forgot to specify that our structure systems are all "Secondary Maintenance" type.
We would like not to create two different features names because, in our context, we'll need to view and edit those value in a web UI interface and users will be able to see only the objects of one channel at a time. Moreover we need to export those values to different systems, so we'll have to "trim" the channel specifier from attribute name.
I was thinking about this kind of solution but as it's a bit heavy to look at and to maintain for export purpose, I was wondering if there is another way.