Copying a multiline text into a single cell in Excel

To paste multi-line content in Excel, all you need to do is double click the new cell (so you see the arrow 'thing' blinking), and paste (ctrl + V):

If you have to do this for more than one cell:

1. Replace all linebreaks in word (^p or ^l) with something you can replace (I use LINEBRK).
2. Paste into Excel.
3. Replace all LINEBRK with the newline/linefeed character generated by Alt+0010 (hold down Alt on your keyboard and then hit 0010 on your number pad) or hit Ctrl + J.
4. Re-do/re-apply Wrap Text in Excel.

Source: Remove Replace or Separate by Line Breaks

I had the same problem now.
I found a different (in some cases a better) solution.
If you can, surround the clipboard content with quotation marks:

"line1


line 2


line 3"