I must have missed this in the documentation somewhere.
All I want to do is have these pages: 1. Most recent from Author (a static URL that we can link to from the navigation) 2. Author Monthly archive pages
Every time I go to create a new archive mapping, I can have EITHER author or author monthly -- and it's random on what will appear (example: I chose "author" from the drop-down list, I get "author monthly" as a result)
I tried creating another archive template and assigning it to be an author index, but that assignment also affected the main entry listing index.
Is there anyway to do this?
Reported on Movable Type 4.1x

You can solve #1 by creating a new index template and specifying an author and a "lastn" value in the <mt:Entries> tag. Look up the specifics in the documentation, but it should look something like <mt:Entries author="Jennifer" lasn="25"> If you do that, you should have no problem also having an archive mapping for author-monthly.
I suggested the fix for #1 on the grounds that it sounds like what you really want is a new index page for the author, and the best way to achieve that is through an index template because that will create a single page. You can make this a little easier on yourself by taking advantage of the cloning capabilities in Movable Type for existing templates to partly automate the process.