Hello.
Congratulations ikandiggit on your discovery of mismatched number notes. I am truly envious as I have always wanted to find such an error but have been unsuccessful.
I am not an expert on error notes, but I know about CBN printing practices with the skip interval of 8,000 and the position number layouts. The reply by woodguy62 is accurate. These error notes were printed in position 43 (X-3), 9696000-9703999.
Here is my opinion. Mismatched serial numbers can be created in two ways. The number reels can become loose or stuck during the course of printing a ream. I call this a "spontaneous" mismatch. Alternatively, the left and right sides could have been set incorrectly by the press operator. I call this a "systematic" mismatch. The number of error notes created by the systematic mismatch can be up to and including the total number of sheets printed in the ream, in this case 8,000.
But wait! For these ELN notes, the mismatch was created by having the 6 on the left increased to a 7. The first 4,000 notes printed should be 9696000-9699999, and they will probably all have the mismatch on the left (9796000-9799999). For the next 4,000 notes, it is possible that the correct serial number was printed because the 6 on the right side clicked over to a 7 while the 7 on the left did not change, so 9700000-9739999 was printed on the left and right sides. Also possible, the 7 on the left clicked over to an 8, creating a different mismatch with 9800000-9839999 on the left. My gut tells me that the latter scenario did not happen, otherwise the press operator would have realized the error after the notes were printed, and these notes would never have been released. So we're probably looking at a maximum of 4,000 error notes if the error was systematic. There's no way to know for sure until more of these errors are found.
I hope this helps!
Mark