I have done the following in the past:

1. pip install libfoo==1.x.x

2. pip install libfoo==2.x.x --target ~/libs/libfoo_v2 # vendor libfoo v2

3.

import sys

import libfoo

original_sys_path = sys.path.copy()

sys.path.insert(0, '~/libs/libfoo_v2')

import libfoo as libfoo_v2

sys.path = original_sys_path

There are caveats of course. But works for simple cases.