Third type of how values must be unique: across fields

Love this module, very useful. I do need a different type of way for my fields to be unique, however. I'm picturing this in the Unique field settings:

Choose whether values must be unique individually or in combination:
o Each of the specified fields must have a unique value
o The combination of values from the specified fields must be unique
x The values from the fields must be unique across the fields.

For instance, I have an "Also known as" field (multi-valued textfield) added to several of my content types. This field is displayed right below the Title. A node of Content type "Author" may have Title = "Mark Twain" and "Also known as" = "Samuel Clemens". I want Unique field to not allow another Author node to be added with Title = "Samuel Clemens". Say someone successfully added another Author node with Title = "Samuel Langhorne Clemens". When they try to add "Also known as" = "Mark Twain", I want it to fail and point them to the existing node.

I've searched but I can't find an existing way to get this behavior. (Taxonomy has synonyms but nobody seems to use them for anything but glossary displays and there's no built in way to turn on "enforcement" of them.)