Read XML nodes into Data Dictionary, C#

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//Rextester.Program.Main is the entry point for your code. Don't change it.
//Compiler version 4.0.30319.17929 for Microsoft (R) .NET Framework 4.5

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
using System.Xml;
using System.Xml.Linq;

namespace Rextester
{
    public class Program
    {
        public static void Main(string[] args)
        {
            string data = "<data><test>foo</test><test>foobbbbb</test><bar>123</bar><username>foobar</username></data>";

XDocument doc = XDocument.Parse(data);
            Dictionary<string, string> dataDictionary = new Dictionary<string, string>();

foreach (XElement element in doc.Descendants().Where(p => p.HasElements == false)) {
                int keyInt = 0;
                string keyName = element.Name.LocalName;
                
                var parent = element.Parent;
                while(parent != null) {
                    keyName = (parent.Name.LocalName + "." + keyName).Replace("data.","");
                    
                    parent = parent.Parent;
                }
                
                while (dataDictionary.ContainsKey(keyName)) {
                    keyName = keyName + "_" + keyInt++;
                }
                
                dataDictionary.Add(keyName, element.Value);
            }
            
            foreach(var x in dataDictionary) {
                Console.WriteLine("keyName: " + x.Key + " value: " + x.Value);
            }
        }
    }
}

Show compiler warnings [ + ] Show input
Compilation time: 0,17 sec, absolute running time: 0,22 sec, cpu time: 0,22 sec, average memory usage: 18 Mb, average nr of threads: 4, absolute service time: 0,41 sec