Duplicate submodules with Git

I have a project in Git that has several submodules, and I need those submodules to be downloaded and the files available in order to use the main project, and in order for the submodules to work I need their own submodules to be available etc. So to set this up I recursively initialise the submodules using git submodule update --init --recursive.

However, I've noticed that many of my submodules have shared dependencies, looking something like this in pseudocode (alpha -> beta represents that alpha has the submodule beta)

my project -> submodule a -> submodule m
           -> submodule b -> submodule m
                          -> submodule n -> submodule x
           -> submodule c -> submodule x

My question is: is there any way of avoiding this duplication using only git, while still having (at least one copy of) the files for each submodule?

I can imagine a solution with symlinks, but it would be preferable if git handled this for me, and I'm not sure whether putting in the symlinks myself would cause problems when updating the submodules.

Ideally I'd love to simplify it down to:

my project -> submodule a -> symlink(submodule m)
           -> submodule b -> symlink(submodule m)
                          -> symlink(submodule n)
           -> submodule c -> symlink(submodule x)
           -> submodule m
           -> submodule n -> symlink(submodule x)
           -> submodule x

Thanks in advance for any suggestions!