In js, why use two encodeURIComponent, and use one? why is it garbled?

var url = context1+"/trade/home/qdmenu/js/appeal_form.jsp?data="+encodeURIComponent(encodeURIComponent(delHtmlTag(data.lABEL_CONTENT),"GBK"));
                window.showModalDialog(url,"","status:no;dialogLeft:"+lef+"px;dialogTop:300px;center=yes;dialogWidth:800px;dialogHeight:200px;scroll:no;help:no;");    
May.11,2021
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