Hi, I've done some reading on this and here's the answer for anybody else that wants to know:
Instead of having separate counters for Like and Share, the counter displays a combined total of likes and shares. This is from the relevant page on the Facebook Developers site:
https://developers.facebook.com/docs/plugins/like-buttonWhat makes up the number shown next to my Like button?
The number shown is the sum of:
- The number of likes of your URL
- The number of shares of your URL (this includes copy/pasting a link back to Facebook)
- The number of likes and comments on stories on Facebook about your URL
- Try clicking the like button on an article and you'll see that the figure next to the Share button increases by 1