For some reason I happened to look at the the writing on three of my Genesis Model 1 AC adapters and I noticed that even though their voltage is the same, all three have a different wattage: 17, 18, and 20 W. Apart from being mildly curious about this, I am also ever so mildly concerned that not putting the right adapter with the right Genesis might mildly harm my least favorite video game system. Pretty sure it doesn't matter, but, you know, it doesn't hurt to ask.
EDIT: Sorry. My now mia Atari Jaguar was my least favorite system ever, not the Genesis.