Double rack baking was less successful. There's no convection fan in this oven to circulate the hot air around (and hardly any features at all, really). That means that you have less flexibility with what you're able cook and how you're able to cook it.
Here's a graph of the oven temperature during the single-rack biscuit test. That first dip is us opening the oven to put the dough in. From there, it doesn't do poorly, averaging out right about where we want it. And, of course, the proof is in the results. The biscuits came out just fine.
For comparison's sake, here's a graph of the same test run in the JB650SFSS, another electric range from GE. As you can see, it's a bit steadier, though perhaps a touch too cool. Still, the biscuits were fine here, too, so you're probably splitting hairs.