Run 2 instances of fivem (testing purposes)

[MancoRuben]

Hey you all! I’m developing a script but I need two clients connected to my server to test it, so I thought running two fivem instances would be a good option. To do this, I’m using Sandboxie, and I followed an issue I read on the forums (link):
*Created 2 FiveM directories (appdata/local/FiveM1 and appdata/local/FiveM2)
*Created 2 GTAV directories (steamapps/common/Grand Theft Auto V1 and 2)
*Setted FiveM1 citizenfx.ini to point to GTA V1 folder, and FiveM2 .ini to GTA V2 folder

However, I can’t get Fivem to launch. It just displays the progressbar of checking files, and when that pops out, nothing happens. I can see the process running both in Sandboxie and the task manager, so my guess is the game is running but no window is displayed, which makes FiveM home page doesn’t show up, so I can’t even move through the menu.
The only thing I think it would be helpful to remark is that when I start fivem with sandboxie, the old progressbar is shown:

And when I open FiveM without Sandboxie, new progressbar is shown (and game is correctly launched)

Both instances run perfectly when opened outside of Sandboxie. I’ve already given file access permissions to appdata folder in Sandboxie settings like the solution of the other issue said, but it doesn’t work either.

GTA V version? Current
Up to date? Yes
Legit or Pirate copy? Legit
Steam/CD/Social Club? Steam
Windows version? 10
Did you try to delete caches.xml and try again? Yes
Error screenshot (if any)
System specifications I5 7400 + GTX 1060 6GB + 16GB RAM
What did you do to get this issue? Trying to run FiveM with sandboxie
What server did you get this issue on? Game isn’t even launched
CitizenFX crash zip file Not getting any
CitizenFX.log file Not getting any
.dmp files/report IDs Not getting any

[system]

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