I am working with conda in Windows. I accidentally installed two versions of pip using python -m pip install --upgrade pip
Now when I run conda list from the base env:

While pip -version gives pip 10.0.0
If I create a new env with conda create --name py3 pip and run pip --version I get an ImportError, however python -m pip --version works:

How can I resolve this?
First of all I tried to replicate your issue and when I updated pip to 10.0.1 using python -m pip install --upgrade pip, the command pip --version seems to work for me. I suppose it was a bug on version 10.0.0. Now coming to the issue that multiple pip versions are showing up in conda list of base, the <pip> one is the incorrect one and must be removed.
You can uninstall one of the pip versions
pip uninstall pip
Now finally run
conda install pip -f
And violla! Everything is back to normal. Next time, you can update pip by using
conda update pip
It is a safer method to update.
Note:-
In this scenario we have also removed the pip from your python installation as well. If you want to use pip in cmd prompt then simply use easy_install pip~=10.0.1 in cmd prompt.