32GB vs 12GB. Enables a lot more. If you don't care about memory and FP64, 2080Ti would be a much better deal than Titan V. V100 vs Quadro RTX 8000 would be more interesting.
Still, I think 2x1080Ti is a better deal than 1x2080Ti and costs the same.
Frankly it probably is, if only because you can do batch processing while still doing more experimental work on the other card.