JSFiddle - React, Tailwind, and code Playground

JavaScript

function ViewModel(){
    var self = this;
    
    self.versionDataByProduct = ko.observableArray([1,2,3,5,6]);
    self.copiedSavedVersionData = ko.observableArray([5,6]);
    
    self.copiedSavedVersionData(self.versionDataByProduct().slice(0));
    
    self.copiedSavedVersionData()[0] = 4;
    
    console.log(self.versionDataByProduct());
    console.log(self.copiedSavedVersionData());
}

ko.applyBindings(new ViewModel());