The approach I use is to have a single incoming notes file for my phone. I then refile those notes into the correct location on my laptop later. It works for me because I realised that when I want to take a note on my phone I usually don't have time for a complete note, so the extra refile step gives me the opportunity to fill it out more at my leisure on my laptop. As an extra benefit though, it means that I only have one file that can conflict, and I can just bias resolution towards the phone's version.