JSFiddle - React, Tailwind, and code Playground

HTML

<span class="clocks"></span> <span class="clocks"></span>

JavaScript

var tmonth=new Array("January","February","March","April","May","June","July","August","September","October","November","December");

elems = document.getElementsByClassName("clocks");
for (var i = 0; i < elems.length; i++) {
	(function(i) { //this puts each set interval in its own unique instance
		var temptime = elems[i]; //save the clock variable in this instance
    var ti = i;
		setInterval(function() {
			var today=new Date();
			var h=today.getUTCHours();
			var m=today.getUTCMinutes();
			var s=today.getUTCSeconds();
			m = checkTime(m);
			s = checkTime(s);
      if (ti == 0) {
      	var nmonth=today.getMonth(),ndate=today.getDate(),nyear=today.getYear();
        if(nyear<1000) nyear+=1900;
        temptime.innerHTML = ndate+" "+tmonth[nmonth]+" "+nyear+", "+h+":"+m+":"+s;
      } else {
      	temptime.innerHTML = h+":"+m+":"+s;
      }
		}, 1000);
	}(i));
}

function checkTime(i) {
	if (i<10) {i = "0" + i};  // add zero in front of numbers < 10
	return i;
}