It is always recommended to group all imports of a single path or source in a single import declaration. These usually happen in a codebase when multiple developers are working on the same codebase. It helps improving code refactoring and code readability as well.
// <!-- index.js -->
import calc from './calc.js'
import { add } from './calc.js'
console.log(add(1, 2))
// <!-- index.js -->
import calc, { add } from './calc.js'
console.log(add(1, 2))