Well, yeah. But that's not because of technology choice or development methodology, it's because simultaneous work by two developers on the same lines of code is fundamentally a really hard problem. It was hard before source control, it was hard with SCCS and RCS, and it's hard with git.
No matter which way you slice it, one of the two developers (maybe both) needs to sit down and figure out what the others' changes do and how they interact with his/her own. That's a wetware problem, not something you can fix with a tool.
That's true. But if both developers are developing out of the same branch, and are checking in small patches at a time, they are more likely to notice the interaction as it is happening and actually talk to each other.
The more difficult problems come when each worked on it for 2 weeks, then they discover a month or two later that there is a conflict - after both have forgotten what they were doing and why they were doing it.
No matter which way you slice it, one of the two developers (maybe both) needs to sit down and figure out what the others' changes do and how they interact with his/her own. That's a wetware problem, not something you can fix with a tool.