Thanks for your replies. They were what I expected but, as I said, I was operating on hope over knowledge.
I had a few reasons for wishing that I could use two converters. One was that I'm new to Nikon, and until I get more comfortable with Capture NX's batching and workflow, I'll be relying on the more familiar ACR most of the time. However, I've learned already that NX does some things ACR can't. It can straighten out my fisheye lines and, as mentioned, it appears to be very good at correcting chromatic abberation on the fly. It would be nice to be able to use NX for those steps and then move over to ACR, at least until I decide to use NX for everything.
So far, Capture NX has been awkward for me, especially when I'm working on jobs that contain several hundred frames. I can't tell yet if the difficulty is within the program itself or just my lack of familiarity with its controls. I'll just have to learn and practice more.
The nice part of all this is that Nikon makes software that's good enough to create the problem in the first place. I used to shoot with Fuji and can tell you that their software is so slow and cumbersome that I never had any desire to use it at all, let alone in conjunction with another program. Lots of people raved about the quality of the Fuji-processed files, but I just couldn't afford the time Fuji required.
Thanks, again. MB