Welp.
Here's the one that was in there. One D:
Box O' brake stuff:
1 D:
No Ds:
I could swear I had at least two more of these but I might've given them to a neighbor. The Spyder came with two dual master cylinders, one marked "Use This" (which I did), plus two aftermarket single masters that came with the pedals:
I had at least one more in the shop--a Brazilian one I bought for Bridget years ago and never installed (and lost and then found). That one has gone missing again but I doubt it's a DD since that car has discs/drums.
And so: ordering yet another.
On the bright side: I found a totally new wiper kit for Bridget in a chip can I got from Alan. Never even looked in there in five years; it's a legit late MG TD wiper rig, looks like, with the motor on top of the windscreen. Thanks, Alan!