The easiest way is to use pip to generate a requirements file. A requirements file is basically a file that contains a list of all the python packages you want to install (or have already installed in case of file generated by pip), and what versions they're at.
To generate a requirements file, go into your original virtualenv, and run:
pip freeze > requirements.txt
This will generate the requirements.txt file for you. If you open that file up in your favorite text editor, you'll see something like:
Django==1.3 Fabric==1.0.1 etc...
Now, edit the line that says
Django==x.x to say
Django==1.3 (or whatever version you want to install in your new virtualenv).
Lastly, activate your new virtualenv, and run:
pip install -r requirements.txt
And pip will automatically download and install all the python modules listed in your requirements.txt file, at whatever versions you specified!
Easiest option is using
venv2, follow these steps:
virtualenv-clone in either
venv1 or a dummy virtual environment
venv_dummy. To create
python -m virtualenv venv_dummy source venv_dummy/bin/activate
(venv_dummy): pip install virtualenv-clone
(venv_dummy): virtualenv-clone venv1/ venv2/