Odd Behavior at a Google Plus Photos Community

As I mentioned in a post in July, I will, on occasion, upload a photo to the Street Photographers Community on Google Plus. In that post, I noted a tendency for Black and White photos uploaded to the community to receive more "+1"s than color photos. Perhaps, that view is a bit subjective, but I'll stand by that observation.

Another oddity I've noticed on that particular community is a discrepancy in the number of "+1"s my photos receive, and the number the photo is credited with. One example of this discrepancy is the photo used in the aforementioned blog post. That particular photo is credited with 32 "1+"s. However, when I check the activity on the photo, it shows that 40 people had given the photo a "1+".
I had noticed this oddity before, but I've only now decided to comment on it. With my latest uploaded photo -seen here - the photo is credited with 14 "1+"s. Checking the activity, I find that 23 people are listed as having given the photo a "1+".

At first, I thought this was some sort of glitch with Google Plus until I began checking the activity on random photos uploaded by other photographers. With every photo I checked (except for mine, of course) there is no discrepancy between the number the photo is given credit for and the names listed in the activity for the photo. If it credits a photo with 45 "1+"s, there are 45 names listed. If there are 14 "1+"s credited to photo X, there are 14 names listed in the activity. After checking a few photos at random, it appears to me that my photos are the only ones that have this difference in numbers.

Why is this?

Who knows?