In the 10k tools on Meta, the posts that show having undelete votes have a count showing that is off by 1. Some of these have no undelete votes showing on the post, so it's not a caching issue.
There are two things you are seeing here.
For the questions that have higher shown on the question than shown in the tools, this is because you're only looking at a time-based filter in the tools. The one with 2 undelete votes, if you look at the 30 day view it shows 3 undelete votes. Undelete votes age away much slower than other votes, if at all.
For the questions that are reported as having 1 undelete vote on the tools, but don't show any on the question, this is because both of them have been undeleted successfully, and were simply re-deleted afterwards. Like close votes, solidified undeletion/deletion votes retain their count even after the choice has been reversed.