string conString = "Host = local;UserName = UID; Password = PWD;Host =localhost";
        var sp = conString.Split(';');
        Dictionary<string, string> keyValue = new Dictionary<string, string>();
        foreach (var k in sp)
        {
            if (k.Contains('='))
            {
                var conSP = k.Split(new char[] { '=' }, 2);
                if (keyValue.All(i =>
                 i.Key != conSP[0]))
                    keyValue.Add(conSP[0], conSP[1]);
            }
        }

var keyValue = conString.Split(';')
                               .Where(kvp => kvp.Contains('='))
                               .Select(kvp => kvp.Split(new char[] { '=' }, 2))
                               .ToDictionary(kvp => kvp[0].Trim(),kvp => kvp[1].Trim(),StringComparer.InvariantCultureIgnoreCase);