USA APC/CVP/ATM - overprint ERROR stamps on USPS Form3817 (#299) rate change

Description

USA 3x "Matrix code overprint ERROR" stamps used pay part of the fee on USPS Form 3817
(new fee rate January 25, 2021)
On Sunday, January 24, 2021, various USA postage rates and fees changed, including the fee for USPS Form 3817; the rate increased from .50 to .55.
--> Since there are virtually no post offices with attended clerk service on a Sunday, that made Monday, January 25 the first day to get a Form 3817 postmarked.  So, how many usages like this (especially with an error stamp) are to be found?  Probably none.
So, if you are a collector of US Postal History, you know that for many years now, the last Sunday in January has been the date when many postage rates and fees increase, but that also makes it difficult to get hand cancels on that first day!
This might be a nice exhibit exhibit item for postal history (or even certain topical or thematic exhibits), as Forms 3817 that have stamps used to pay for the fee are extremely difficult to find (since mostly PVI strips or meters are used to pay for this fee).   3 different ERROR overprint stamps pay the .55 fee.  The .15 stamp I had originally bought to use for international rate postage, but I had some left and used this one as part of the postage.  The {{detail_product_description}}.34 stamp was the rate for postcards at the time.
Please note that for privacy's sake, certain elements of the scan have been obscured, the actual form you'll receive will have this information shown.
Here's the interesting part:
The OVERPRINT ERROR of #CVP91b which was bought on August 26, 2018 from a newly converted machine (and is one of the earliest available overprint usages from August 2018 when all the machines in the USA were starting to be converted (relatively few collectors were on hand when machines were being converted, which ranged from August to about October 2018!).  The main difference in these is that the serial number from the new machines begins with a number instead of a letter, and that is how CVP91 & CVP91b are distinguished.
Due to the machines being delivered to post offices with an incorrect default setting (for plain unprinted labels, rather than the flag-preprinted labels), the machines printed either the USPS Eagle Forever imprint or the Matrix code imprint for other values!   Apparently the people setting up the machines (usually 3rd party contractors), nor USPS personnel noticed this problem initially; settings were changed at the machines eventually... but proper usages of these type of overprint error stamps are difficult to find ...
Generally USPS Forms 3817 (which are also known as "Certificate of Mailing") are mostly found with a "PVI" strip issued by the Post Office clerk (or perhaps a meter strip from a private company); finding them with stamps or ATM stamps is fairly scarce, and even scarcer if ERROR stamps are used !
Due to irreplaceable nature of this kind of an item, will ONLY ship via tracked mail (as per eBay guidelines to ship items with tracking).  Foreign shipments possible, but due to tracking requirements, will only be possible via the eBay Global Shipping Center.
Note: I only have 1 lot available with this combination overprint error stamps from the new Form 3817 fee change; the image shown is of the exact item that you will receive.