diff --git a/collects/racket/contract/scratch.rkt b/collects/racket/contract/scratch.rkt
new file mode 100644
index 0000000000..4467506496
--- /dev/null
+++ b/collects/racket/contract/scratch.rkt
@@ -0,0 +1,59 @@
+#lang racket/base
+(require racket/contract)
+
+(->i (#:kwd1 [x number?]
+      #:kwd2 [y number?])
+     #:rest [x any/c]
+     any)
+;=> duplicate identifier 'x'
+
+
+#|
+test cases:
+
+(->i (#:kwd1 [x number?]
+      #:kwd2 [x number?])
+     (values [y number?]
+             [z number?]))
+=> duplicate identifier 'x'
+
+
+(->i (#:kwd1 [w number?]
+      #:kwd1 [x number?])
+     (values [y number?]
+             [z number?]))
+=> duplicate keyword
+
+
+(->i (#:kwd1 [w number?]
+      #:kwd2 [x number?])
+     (values [y number?]
+             [w number?]))
+=> duplicate variable 'w'
+
+
+(->i (#:kwd1 [w number?]
+      #:kwd2 [x number?])
+     (values [y number?]
+             [y number?]))
+=> duplicate variable 'y'
+
+
+(->i (#:kwd1 [w number?]
+      #:kwd2 [x number?])
+     (values [y number?]
+             [w number?]))
+=> duplicate identifier 'w'
+
+(let ([values (λ (x) x)])
+  (->i (#:kwd1 [w number?]
+        #:kwd2 [x number?])
+       (values number?)))
+;=>  no error(?)
+
+(->i (#:kwd1 [x number?]
+      #:kwd2 [y number?])
+     [x number?])
+;=> duplicate identifier 'x'
+
+|#