Hi, for SEO users multiples URL are a big problem
let me explain you some case :
1. you offer a permalink not rewrited by a 301, google will find 1 content on 2 urls
2. your url look like
http://mysite.com/my/url.html, some bot will have a look what there’s in
http://mysite.com/my/
for you this page should be :
http://mysite.com/my.html by modx rule. SO 1 content on 2 urls
many other case can be found, u MUST do a 301 to be seo strict if u do not ask for final URL.
Otherwise everytime that u make a content, you content will be dilute by your duplicates.
By the times, the competition for content is hard on the web, so be strict on url is VERY IMPORTANT
regards
Norbert