These are 'per favour' strikes of course (I must have had 100s done in the 1980s although I didn't obtain these particular examples .... I favouredJeffharris wrote:The letter rate in June 1985 was 33c. Here we have a 1c. stamp and 10c. stamp with strange looking cancels!!
the 1c Antarctic Ship stamp for my postmark obsession at the time )
Even though this is the case, I don't believe that anyone "fiddled" with the datestamps just to make up 'a curiosity' or two for a postmark collector.
Naturally, some examples on commercial covers would be ideal to prove that this variation in the datelines was 'constant' for a period of time.
Unfortunately, my "Medicare Hoard" was only accumulated from late 1987 so I'm not likely to find some more examples (if they exist) without a
bit of luck.