Am I allowed start Intellij twice?

I really want to start intellij twice.

I know, I can open a second window in a new window, but:
- If one window "optimize performance", both windows are blocked.
- If one compiles a large project, both windows are sometimes dead (only gray background shown).
- If I close a windows, it seems not to free all memory.
- The garbage collector should work on two small instances better than a big instance.

It seems, Intellij use one or more ports to prevent double starting (and maybe also intellij licences?).

The only advantage I see is to prevent opening the same project twice. But if Intellij checks licences over a network it can also check for the same project opened in different instances.

Or should I open an request?