The pin circled in the photo of cob 109c appears only on this version and is probably an error but is found on multiple copies. Notice on cob 109d that there are two closely spaced pins almost everywhere that there is a single pin on the other late versions, 109 and 109c. These “double pin” versions have also been found for cobs #123 - Home, Sweet Home and #247 - The Devil's Dream.
See the comparison photos at the end of this page to quickly identify the different versions.
109 comparison photos
The different versions of cob #109 can be quickly identified by comparing the grouping of pins shown in the first photo. All but versions 109 and 109c have easily identified patterns. To differentiate versions 109 and 109c a pattern of three notes plus octaves are found on the opposite side of the cob where there is one note with two pins on version 109. Also, the extra single pin (error?) on 109c can be located for verification. Note that late versions of 109 are also found without the single pin error and without the extra pin on the one octave note. This may be a random pin count error on the later versions that just happens to occur at this location. More samples are required to establish a pattern.