A dyno is nothing more than an elaborate bathroom scale, or something like this:
View attachment 1716051249
If you've worked around gauges or insturments of any kind, you know that they can be off, or way off. Usually a dyno that reads high is called a "happy" dyno, etc. So if the engine reads at spec on one dyno, and lower on another, which one to believe?
However, a leakdown and compression test is way quicker than hauling it to a different dyno. Don't get stuck racing dynos.