The char class \R is defined to be \u000D\u000A|[\u000A\u000B\u000C\u000D\u0085\u2028\u2029].

Therefore, the regex \\R{2} must match the sequence \r\n (first \R matches \r, and the second \R matches \n).
In fact, it does not.

import java.util.regex.*;

public class RR {
    public static void main(String[] args) throws Throwable {
        Pattern p = Pattern.compile("\\R{2}");
        System.out.println(Boolean.toString(p.matcher("\r\r").matches()));
        System.out.println(Boolean.toString(p.matcher("\r\n").matches()));
        System.out.println(Boolean.toString(p.matcher("\n\r").matches()));
        System.out.println(Boolean.toString(p.matcher("\n\n").matches()));
        System.out.println(Boolean.toString(p.matcher("\r\n\r").matches()));
        System.out.println(Boolean.toString(p.matcher("\r\r\n").matches()));
        System.out.println(Boolean.toString(p.matcher("\r\n\n").matches()));
        System.out.println(Boolean.toString(p.matcher("\n\r\n").matches()));
        System.out.println(Boolean.toString(p.matcher("\r\n\r\n").matches()));
    }
}

prints the following (expected all 9 results be 'true'):

true
false
true
true
true
true
true
true
true