I do not believe that is a good pattern. First, two devs probably should not be touching the same functionalities (if they are, they ought to be basically pair programming). So diffs should be orthgonal. If diffs are landing in the same branch, each dev should be using their own feature branch, and ideally PRing them back to the branch, but for small hacks, merge is fine.

Think fractally. The farther you get from master, the smaller and more atomic each commit should be.

If your merges are taking lots of coordination or failing to auto-merge, you probably have some poor engineering hygeine at play. Every time I've had merge fails, it's due to haste/sloppiness or a dev branch diverging too much from a mainline.