Me: One?
Optometrist: Wrong! How dare you! Get out of my sight!
I hate when you get it wrong and they poke your eyeball.
When my wife was working she’d ask, “Which is better or are they the same?”
If you don’t see a difference, you are already very close to the optimal correction and a subtle change in either direction is unnecessary. They will still go ahead and try fine-tuning the prescription and when you tell them that A and B are the same, they can fall back when they add another correction. A and B might currently be the same, but if you add C, A+C could be better than B+C.
If it isn’t obvious, you’re done. The weaker of the 2 lenses is right for you.