Compress-a-sequence

During my attempt to learn LISP/Clojure, I tried the problems in www.4Clojure.com

4Clojure problem #30 :

Write a function which removes consecutive duplicates from a sequence.

so that

(= (__ [1 1 2 3 3 2 2 3]) '(1 2 3 2 3))
and


(= (__ [[1 2] [1 2] [3 4] [1 2]]) '([1 2] [3 4] [1 2]))

My solution :

;; ywidyatama's solution to Compress a Sequence
;; https://4clojure.com/problem/30


(fn dedupstr2 [s] 
  (reduce 
    (fn dedup-reduce [seq_or_n1 n2]
      (let [lastn1 
        (if (seq? seq_or_n1) 
          (last seq_or_n1)
          seq_or_n1
        ), seq1 (if (seq? seq_or_n1) seq_or_n1 (seq [seq_or_n1])) ]
        (if (= n2 lastn1)
           seq1
           (concat seq1 (seq [n2])))
      ))
    s
    )
)