had this problem also a while ago. Hope I understand you right.
There is no option under clothsim cache like for particles where you can choose external cached sims.
the way i did it was to cache the clothsim and cut and pasted all files into a new subfolder directory to save it. I also named the simcaches inside blender that way I could remember what i did before the cache.
Now when I cached every different versions and saved it to my subfolders it was and is possible to copy them back to ther root cache folder. Now you need to name it in clothsim correctly like the cache file. and it works.
Not realy sure if that is what you need but it works. Don`t know why there is now “external checkbox” option to choose the cache files in clothsim and maybe i did complete stupid thing but could not figure out a better way to use different cachefiles with clothsim.