It seems plausible to me. I assume that when you are doing a comparison, you are comparing a single source to a memory (does anyone do comparisons by playing two synchronized sources together, possibly into different ears?) In that case, I can well imagine that listening to multiple live performances primes one's mind to remember clearly how a given presentation sounded, and to pick out small differences, precisely because live performances are all slightly different. I would further imagine that performing a piece, and particularly practicing with the rest of the orchestra or conducting a practice, further enhances one's ability to notice and characterize small differences.

Of course, this might be utter nonsense, and I will bow to bayindirh's judgement on that!