There are a couple of things going on here. First, note that the Explore view does not actually show the users who have identified that taxon the most, rather it shows the users who have added the most identifications to observations that currently have that taxon (or descendants) as the observation taxon. This is intentional:
Related feature request here.
Second, I do think there is an actual bug, stemming from an issue with Complex Bombus lucorum. At one point Bombus terrestris 57516 was listed as a child of Bombus lucorum 61856. @loarie reverted a taxon change, and I think something ended up a little wonky, because some B. terrestris IDs still think they are underneath 61856 even though B. terrestris knows that it’s under 1092510.
As a result, when you query for IDs of 61856 or its descendants (the list shown on an observation page), you get 118 for tony_wills, who has IDs of B. terrestris that think they are under 61856.
Probably the same or a similar bug is causing at least some of the issues report here.