Is a journal that is on Beall's list but is also in Scopus a predatory journal?
Indexing in Scopus does not necessarily mean that a journal is not predatory. From the guidelines for being indexed in Scopus:


  -The Journal should consist of peer‐reviewed content
  
  -The Journal should be published on a regular basis (have an ISSN number that has been
  registered with the International ISSN Centre)
  
  -Content should be relevant and readable for an international audience (at minimum
  have references in Roman script and English language abstracts and article titles)
  
  -The Journal should have a publication ethics and publication malpractice statement


These guidelines could potentially be satisfied by a journal that Beall's list considers predatory. Many pay-to-publish journals advertise "peer review", but it may not even be solicited/may not matter in the "decision" to accept the manuscript. 

There also can be information on why the specific journal or publisher is considered predatory on https://scholarlyoa.com. I generally have high confidence in Beall's list--predatory journals do not have a great incentive to turn legitimate.