Here's a solution with Acrobat javascript using the attached files. It is not thoroughly tested, so check the results very carefully.
I'm guessing it's not possible for the script to know in advance what all the filenames are by any simple convention (e.g., named something static followed by a number in the range 1-469), since your example has "1212" in the name. One of the biggest challenges with Acrobat javascript automation is working within its security restrictions. Acrobat cannot enumerate all of the file names, so it has to know in advance somehow.
For that reason, this is a two step process that starts with a bash script. Place the listfilenames.command file in a directory containing all 938 PDFs (and no other files), then double-click it to execute. It will list the contents of the directory and save it to a file named "filenames.txt." Now we have a file that the Acrobat javascript knows the name of and can read, and it contains the names of all of the files.
Now open Acrobat's javascript debugger (press command-J). You may need to enable javascript, javascript debugger, and interactive console in Acrobat's preferences first. In the console area at the bottom remove any existing text and replace it with the javascript code copied from "Acrobat javascript.txt." Then select the entire script in the console area and press shift+enter to execute (I think it has to be shift+enter, the key in the numpad, not the return key).
It will ask you to open a PDF file. Pick any PDF in your working directory. It doesn't matter which one - Acrobat won't do anything special with that particular file - this is only so the script can discover the directory containing all of the PDFs.
Now the javascript will open the filenames.txt file from that directory and thereby discover the names of all the files in the directory.
It then considers only PDF files whose name contain a space (you should have 469 of them). For each file whose name contains a space ("DUT65-1212 Investments BCM.pdf"), it will look for a PDF file with a name identical to the part before the first space ("DUT65-1212.pdf"). If there is such a file, it will save a new pdf that is a concatenation of the two, named like the first file with "A-" added to the beginning ("A-DUT65-1212 Investments BCM.pdf").