If you look at any site's reputation league for the current week, month, quarter or year (but not for any past week, month, quarter or year), every user appears twice.
This seems related to this bug report (which is marked as completed), but that one only affected a few users, while this time every single user seems to be affected.
Note that this also affects meta, so it does not seem to be a side-effect of the server move.
Proof screenshot: