Maps can have more complex values as keys, which means that you could have a trickier situation to deal with when there are merge conflicts. Let's reuse our previous example and change the keys into something more involved:

const myMap1 = Map.of(
  Map.of('name', 'one'), 1,
  Map.of('name', 'two'), 2,
  Map.of('name', 'three'), 3
);
const myMap2 = Map.of(
  Map.of('name', 'two'), 22,
  Map.of('name', 'three'), 33,
  Map.of('name', 'four'), 4
);
const myMergedMap = myMap1.merge(myMap2);
const myMergedWith = myMap1.mergeWith(
  v => v,
  myMap2
);

console.log('myMap1', myMap1.toJS());
// -> myMap1 { 'Map { "name": "one" }': 1,
// ->          'Map { "name": "two" }': 2,
// ->          'Map { "name": "three" }': 3 }
console.log('myMap2', myMap2.toJS());
// -> myMap2 { 'Map { "name": "two" }': 22,
// ->          'Map { "name": "three" }': 33,
// ->          'Map { "name": "four" }': 4 }
console.log('myMergedMap', myMergedMap.toJS());
// -> myMergedMap { 'Map { "name": "one" }': 1,
// ->               'Map { "name": "two" }': 22,
// ->               'Map { "name": "three" }': 33,
// ->               'Map { "name": "four" }': 4 }
console.log('myMergedWith', myMergedWith.toJS());
// -> myMergedWith { 'Map { "name": "one" }': 1,
// ->                'Map { "name": "two" }': 2,
// ->                'Map { "name": "three" }': 3,
// ->                'Map { "name": "four" }': 4 }

You use the exact same approach here—you use mergeWith() to deal with conflicts by just returning the original value. Key value conflicts are detected using deep equality, so it doesn't matter if you're merging maps with simple keys or with maps as keys.