JSFiddle - React, Tailwind, and code Playground

HTML

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

JavaScript

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
		setInterval(function() {
			var today=new Date();
			var h=today.getUTCHours();
			var m=today.getUTCMinutes();
			var s=today.getUTCSeconds();
			m = checkTime(m);
			s = checkTime(s);
			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;
}