How to Prevent Map from Mutating Data in Javascript [duplicate]

I have an object array that looks like this:

rawData:
0: {name: "cat", count: 2}
1: {name: "dog", count: 5}
2: {name: "fish", count: 3}

and I have a translatedData that multiplies the count field by 2.

newData:
0: {name: "cat", count: 4}
1: {name: "dog", count: 10}
2: {name: "fish", count: 6}

I use the following calculation:

let newData = Object.assign({}, rawData);

newData = Object.keys(newData).map(key => {
  let newValue = Math.round(newData[key].all*2);
  newData[key].all = newValue;
  return newData[key];
});

I use a map to perform this calculation. My issue is when when I console.log both these arrays they both have the calculation. I want the rawData to have its previous state and not be affected by the calculation.I thought object.assign would fix this. What am i doing wrong?