It is not possible to open two different solutions on the same tenant in the same studio installation instance.
But if for example you have to copy from one solution to another, both solutions on the same tenant,
you don’t have to make screenshots from the source solution and then implement captured options on the target solution.
It is absolutely permitted to open two solutions on the same tenant from two different computers.
It is even more comfortable if you take a VM instead of the second one, or you can also use a remote controlled computer to open the second solution.
The only thing you have to care of – you need two different development users for that, because you can’t logon on the same tenant with the same user twice.