I'm not sure if this is the best or only way to do this but one option would be to create multiple users. Say 'User' and 'User-home'.
Each user has his/her own home directory and so can be configured as you wish by making changes to ~/.profile
or ~/.bashrc
for example.
The problem here is that you probably have data you want to share between both users so in the home Directory of user create a subdirectory called 'Data' and in the home directory and a symbolic link to it in the home directory of 'User-home'.
ln -s /home/User/Data /home/User-home/Data
You will also probably want to change the primary group of 'User-home' to match that of 'User' with sudo usermod -g User User-home
In this way you have two users who can access each others files with different settings. For each user any file in ~/Data
is the same file.