Mme. Owl made the mistake of spending the night out hunting, so I was able to do some basic science on her eggs while her back was turned.
I can't tell the eggs apart, so I can't say which is the first or second one laid. I can say the following: one of the eggs weighs 20.0 ±0.2 grams and measures roughly 36.44 x 31.75 mm, and the other egg weighs 20.6 ±0.2 grams and measures roughly 36.35 x 32.1 mm. (My uncertainty about the measurements is due to the difficulty of being sure that I was measuring the major and minor axes, and wasn't a little off in some direction. A measuring box with sliding sides would eliminate that problem, but I haven't seen such a thing.)
Comparing these numbers to Gehlbach’s (see The Eastern Screech Owl, pg. 92), these eggs are around 2 grams heavier, 1 mm longer on the major axis, and 2 mm on the minor axis.
Larger and heavier than average should be a good sign for the eggs. Exactly why, is a matter I'm debating with myself. Presumably, either slightly larger owlets will hatch-out, or a larger yolk sack will mean greater food reserves for the developing fetuses. I’ll have to consult my raptor rehabber, but any other bird experts are encouraged to weigh in.
Regrettably, routine weighing and measuring won’t be possible, as interesting as those numbers would be (the weight of an egg decreases as the embryo inside develops and uses-up its yolk sack, so charting the changes in weight over time would be interesting, for a start), because Mme. Owl will begin near-continous brooding with the arrival of the third egg. At that point, I'll be leaving the nest alone as much as possible.