open TELEMAC-MASCARET The mathematically superior suite of solvers

Hello

You can add both paths like you've written, but be careful to not erase your original path, you should write:
export PATH=/home/.../python27:$PATH
for each version.
to load the config file containing the two versions (assuming that it is located in folder "configs"), you add the line
export SYSTELCFG=/home/...location_of_telemac.../configs/systel.cfg

I hope this helps

Riadh