A few months ago we were having a discussion about regular and replacement notes with matching serial numbers. The only example I could find at the time involved two 1975 $50 notes. I have just come across another, in the CPMS Newsletter for April, 1996. 1986 $2 notes with serial numbers EBZ2634466 and EBX2634466 are illustrated. The EBZ is a regular note, and the EBX of course is a replacement.
These two notes have the SAME face and back position numbers, and were found in the SAME bundle!