In a recent question I made, one of the answers pointed to another answer in another question where a way to explore the forks and clones of a public Github repo was shared.
I believe part of the confusion is that the graph shows 4 cloners (blue line), and the label is saying 3 unique cloners. Other than that, it should be interpreted as:
git clone
command was executed against the repo, so all of your different devices, yes.