As it currently works, the Populist badge requires the accepted answer to have at least one more vote than 10, and the highly upvoted answer to have at least one more vote than double, resulting in a very strange minimum requirement of 23 votes for the answer that earns the badge.
Every other badge on the site works on a "greater-than-or-equal" basis: you don't get the Famous Question badge for a page with 10,001 views, it triggers at exactly 10,000. The Reversal badge doesn't require you to get a score of +21 or the question to get a score of -6, it triggers at exactly +20 and -5.
I would suggest that the badge as it's currently implemented should be tweaked so that it also functions on a "greater-than-or-equal" basis as well:
A highest-voted answer to a question with an accepted answer with a score of at least 10 that has at least double the score of the accepted answer.
This would make the minimum requirements make sense as nice, round numbers — 10 votes for the accepted, 20 votes for the voted. A few new badges might be retroactively awarded this way, but I feel like it would work.
This question may seem like a duplicate of this proposal here, but that one proposes removing the restriction of 10 votes for the accepted answer. Every other question I could find either recommends clarifying the description of the current functionality without changing it, or changing the functionality to something entirely different.