using System;
using System.Linq;
using System.Text.RegularExpressions;
public class Test
{
	public static void Main()
	{
		var s = @"this comes before selection
this is on the same line %% this is the first group and it can have any character /[{3$5!+-p
here is some more text in the middle
this stuff is also on a line with a comment %% this is the second group of stuff !@#%^()<>/~`
this goes after the selections";
		var result = Regex.Matches(s, @"%%\s+(.*)")
		            .Cast<Match>()
		            .Select(p=>p.Groups[1].Value)
		            .ToList();
		Console.WriteLine(string.Join("\n", result));
	}
}

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