Pictorial Postmark Predates Stamp Issue Date By 2 1/2 Years

I recently acquired about 300 postcards and envelopes related to Ocean Grove, NJ, c.1980's. This cover appears to be unique for several reasons, especially the righthand pictorial postmark being about 2 1/2 years earlier than the issue date of the 20c stamp.

I'm new to covers so my question is - Is this usual? Is it IAW USPS regs? Etc?

Also, it certainly isn't the First Day of Issue for either stamp. Again, is this usual??

I have two of these. Would it be worthwhile to try to sell one/

Thanks for any responses.

Modern postal history makes for a fascinating collection. Sounds like you have a great group of covers from one town. Do not expect to get much for your duplicate of this cover but you never now who else my want it. The post office at Ocean Grove NJ should have a great history. Enjoy researching it.

Pictorial postmarks like this are applied locally and the cancel devices often retained for many years afterwards, rather than ever being "sent back" for destruction, etc. It is a contrived curiosity and obviously not a true pre-date. Unusual, but of only nominal vaue.