Generally, yes—within the same model run. However, Koken reused number blocks across different decades. A “No. 5” chair with serial 12,000 is different from an “Imperial” with serial 12,000. Always consider the model name first.
Disclaimer: This blog post is for informational purposes. The Koken Barber Chair Company has changed ownership over the years, and original factory records are not widely distributed. vintage koken barber chair serial number list