Need Help 1982 Roc Cover Postmark Error?

wondering about two covers I have from Republic of China (Taipei)
This series stamps were not issued until 1994 , yet are meter stamped with 1982 dates on the covers.
I was wondering how was this possible this Museum did not even open until 1986 yet these have 1993 issued stamps on them and 1982 canceled postals.
These came from an uncle who mentored students in China around that time period.
I took these to a local stamp dealer and he did not know. He told me the stamps were not anything special, but I like them.
http://flic.kr/p/9cPhVH
http://www.flickr.com/photos/jenniesuephotos/538

I don't think it is 1982...I think it is the 82nd year of the Republic. The Republic started in 1912, so that would seem to be correct. Thoughts, anyone?

That makes all the sense in the world to me Cjd. I should have known not to interpret this cover to be read as a "western Item". That is so helpful and I kindly thank you and I will use this shared knowledge in the future on other china postmarks.

This formula will work for ROC/Taiwan, but not for PRC or older China. Traditionally, the imperial Chinese calendars started the year count over with a new emperor's reign. So, for imperial China, Manchukuo, etc., you'll need to figure out whose reign you are dealing with.

Manchukuo used Japanese dates, right?

During this era, Japan ran their years from the start of Hirohito's reign, in 1926. Manchukuo used the creation of the new state, in 1932, as year 1, and then the accession of Pu-Yi in 1934, as the new start point (a new year 1).