Is "more commonly" the same as "most commonly"?

"Though the prosecutor's fallacy typically happens by mistake, in the adversarial system lawyers are usually free to present statistical evidence as best suits their case; retrials are more commonly the result of the prosecutor's fallacy in expert witness testimony or in the judge's summation".

What does "more commonly" mean here? Just "most commonly"?

We use "more" when we're comparing two things, and "most" when comparing more than two things (and one of them is superlative among those things).

In this case, the writer used "more" because they were (implicitly) comparing two things: retrials due to a prosecuting attorney presenting the prosecutor's fallacy to the jury and retrials due to expert witnesses or judges presenting the prosecutor's fallacy to the jury. The claim is that the second situation more commonly results in a retrial than the first one.

If they said, "retrials are most commonly the result of the prosecutor's fallacy in expert witness testimony or in the judge's summation", they would be claiming that this is the most common of all reasons for a retrial, not just that it is more common than one other cause under consideration.