Can you layer hydroquinone 2% to reach the same efficacy as 4% in treating hyperpigmentation under eyes or on rest of face?

I don't know: That is a very good question that I often wonder, being prone to post inflamatory hyperpigmentation myself. I wish we know. I wish anybody knows! Use twice the amount use twice as often? For how long? How come it works on one spot and not on another? I know sun exposure makes things worse, the rest,??? IDK! Aslo I worry about effects on the cornea applying too close to the eyes.