regexp question

Question

Regular Expressions

I have a large number of paragraphs starting with the same headings.
For example

Gen\r\n
text
Gen\r\n
text
Gen\r\n
text
Gen\r\n
text

I want to make sure that only the first one remains. Gen

\r\n
text
text
text
text

Answer 1

so if they are the same, regular expressions are not needed. You can just replay. for example
$title='Gen\r\n';
$text='Gen\r\n
text
Gen\r\n
text
Gen\r\n
text
Gen\r\n
text';
echo $title.str_replace($title, '', $text);


Answer 2

Delete every second line after the first:

Regex.Replace(text, "(?<=\r\n)(.+\r\n)(.+)", "$1")

Answer 3

We enter the text into the array by paragraphs, run through the odd elements, if the element is equal to the previous odd one, we delete it. Then again we glue the array into a string.