1. I was using VCV Rack on Windows, but I think my friend was not, so you may need to tweak Git's line ending settings
2. Some changes you just don't want to merge. The other person could have different audio output settings. There can also be rounding errors in the knob values so sometimes the values can be edited slightly even if they were 1.0 before, even if you don't think you changed them, which makes merges a little noisier. But `git add -p` made short work of cleaning that up.
Edit: This is also assuming that you coordinate who takes turns editing at one given time - "ping pong" is easier than free for all.
A couple of friends and I are experimenting with collaborating using Github and pull requests.