uniquify-strip-common-suffix

uniquify-strip-common-suffix is a variable defined in `uniquify.el'.
Its value is

t

Documentation:
If non-nil, strip common directory suffixes of conflicting files.
E.g. if you open /a1/b/c/d and /a2/b/c/d, the buffer names will say
"d|a1" and "d|a2" instead of "d|a1/b/c" and "d|a2/b/c".
This can be handy when you have deep parallel hierarchies.

You can customize this variable.