Issue: LAMBDA-LIST-DUPLICATES (Version 1)

[Jeff Dalton <jeff%aiva.edinburgh.ac.uk@NSS.Cs.Ucl.AC.UK>]

Current practice:
  Both PopLog Common Lisp and KCL allow variables to appear more
  than once in a lambda-list.  In the three suggested test cases,
  they both have the later binding current in the body of the form
  and so return the values 2, 1, and 1 respectively.

  In addition, both allow variables in other cases, specifically:

  KCL:
    ((lambda (a a) a) 1 2) => 2
 
  PopLog:
    ((lambda (a a) a) 1 2) => 1