The Greek letter paradox is seeing the same symbol in two contexts and assuming it means the same thing. Maybe it’s used in many contexts, but I first heard it in the context of comparing statistical models.
I used the phrase in my previous post, looking at
α exp(5t) + β t exp(5t)
α exp(4.999 t) + β exp(5.001 t).
In both cases, α is the coefficient of a term equal to or approximately equal to exp(5t), so in some sense α means the same thing in both equations. But as that post shows, the value of α depends on its full context. In that sense, it’s a coincidence that the same letter is used in both equations.
When the two functions above are solutions to a differential equation and a tiny perturbation in the same equation, the values of α and β are very different even though the resulting functions are nearly equal (for moderately small t).