Can I use 2 Minecraft accounts on a PC?

I would like to play in my PC with 2 minecraft accounts at the same time but if I try to play with 2 account I can play full version with the other account, and because the other demo, you can play both accounts fully verso in a PC? If yes how?

Use already, but do not play at the same time. You can play active only 1 char. I had 3 accounts at GAMIGO years ago, which I used as needed. Everything from the same PC.

I've always used Craften Terminal, or even the MagicLauncher or MultiMC. In these clients you could just open a new instance with another account and you already have two Minecraft windows with different accounts.
I think that with the new standard launcher you can only open one instance.
I'm not sure because I have not played Minecraft for years.

However, even if you have multiple instances open with different accounts, you can always actively play only with one client. The other client is automatically "inactive" (as if you had pressed the Esc key).

Thanks, I'll try

Start Minecraft 2 times and log in with both accounts. Strange question.

Is it so easy to use at the same time?

Naturally. I do that often enough myself.