Can I be signed in to two accounts of the same site at once?

Yes. That is what workspaces are for.

Each workspace has its own tabs and its own cookies, so its sign-ins stay inside it. Put one account in each workspace and both stay signed in at the same time.

1. Press New workspace in the left rail.
2. Open the site and sign in to the second account there.
3. Switch between workspaces from the rail.

You can have as many workspaces as you like, on every plan.

Good to know

• To clear a workspace, use Settings → Privacy & security → Forget... and pick the workspace. Minda lists what will go before anything goes.
• A workspace can have its own proxy, set in its Connection dialog.
• The AI agent can work in a workspace's sign-ins when your own words name it, such as "in the Shop B workspace". Text on a web page never picks a workspace for it.
• Workspaces keep accounts apart inside Minda. They do not change the address sites see. For that, use Hide my IP or a proxy.