Guinea new signature variety 500-franc note confirmed

I’m researching an interesting 1998 note variety for Guinea. As you can see, both 500-franc notes (Pick 36) shown below are dated 1998. However, the note with the AO prefix has a signature variety that’s different from the signature combination on the note with the FB prefix. The odd thing about this discovery is that the second combo is found on all other denominations in the 1998 series, as well as the 1985 series before it, and the 2006-present series.

The SCWPM doesn’t include any mention of signature varieties for Guinea, but my new catalog does. I have seen it on the 100-franc note from 1998 (prefix AT), but not on the 1,000- or 5,000-franc notes (both AA). So, if you have this (or any other previously unlisted variety) signature on other notes, please send me 300-dpi scans of same.

I’d also appreciate any help in explaining this short-lived signature combination, as well as identification of the signatories by name.

Finally, I notice that the 15th edition of the SCWPM has drastically dropped the values for Guinea specimens P13-P15 as well as P20-P28. If anyone has any thoughts on the accuracy of the new pricing, I’m all ears.

Courtesy of Rui Manuel Palhares.