This is probably a result of different tab settings between you and your colleague.
I recommend that first, you standardize on tabs vs spaces, and if I recall correctly, it is recommended to use spaces with Python.
I do not have version 10.* so I cannot tell you the exact items to click on (maye somebody with a better memory of that version will be more specific). But here is what I would do:
Go to Advanced -> Configuration.
You need to find the Word Wrap and Tab settings. You can search the help for "Tabs" to figure out where to make the setting changes.
Once you have found the section for Tab settings, you will see a drop down list labeled "Select Extension for Settings or Default" which will contain "Default" as the first item. I would add an item for Python files by clicking the "Change List" button. Add the .py extension (or whatever extension you use). Then, making sure that the new extension is selected in the drop down list, change the "tab stop" and "indent spaces" settings to what you have agreed upon.
Additionally, you might need to perform some cleanup of the files to make sure that your indentation is not corrupted any further than it already is.
I hope this helps!