id	summary	reporter	owner	description	type	status	priority	milestone	component	version	resolution	keywords	cc	difficulty
1125	procedures allow to pick the same name for different arguments	certainty		"Currently the following is legal:

(lambda (x x) x)
(define (foo x x) x)

According to the standard it is an error for a variable to appear more than once in the formals of a procedure. 
Guile and Gambit produce an error whereas Gauche and Scheme48 don't.

It appears reasonable to me to reject code like this and produce an error.
"	defect	closed	minor	4.11.0	compiler	4.9.x	wontfix