CODE EXAMPLE FOR JAVASCRIPT

array with object same keys

const arrays = [{ name: "foo1",value: "val1" }, {name: "foo1", value: ["val2", "val3"] }, {name: "foo2",value: "val4"}];

const map = new Map(arrays.map(({name, value}) => [name, { name, value: [] }])); 
for (let {name, value} of arrays) map.get(name).value.push(...[value].flat());
console.log([...map.values()]);
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