Windows: Keyboard overlay does not allow one button to trigger multiple keys.

Description

Windows os: When using a keyboard overlay to add extra buttons on screen for DOS games, you cannot configure an on screen button to perform 2 keystrokes, i.e. Shift-F5 or Alt-e.
The Libreto docs overlay page metions allowing multiple button presses and gives example of overlay0_desc0 = "left|up...
But when attemping this with keyboard keys, retrok_lshift|retrok_f5, no key is triggered.

Expected behavior

Pushing a multiple key configured on screen button will execute both buttons together in game.

Actual behavior

No key press is triggered.

Steps to reproduce the bug

Edit existing keyboard overlay config file to add a key modifier to any key. i.e. Retrok_lalt|retrok_e
Load DOS game which uses a keyboard and has multiple key combo inputs. X-wing uses "alt - e" to eject.
Press on screen button and observe nothing happens.

Version/Commit

Windows 10
Retroarch build date Jan 21 2022

Reproduce the issue on Windows 10 with a keyboard overlay configuration using Retrok_lalt|retrok_e or Retrok_lshift|retrok_f5, then trace the keyboard overlay handling while running the X-wing DOS game. Done means an on-screen button configured with two keys triggers both keys together in-game.