Serialport object behavior when copied

I am reworking some code which used serial objects. As those are due to be removed, I am rewriting using serialport. In principle, I want to share the serialport object by copying it into the global variable space and retrieving it whenever a function is called.

My question now: Since serialport creates and opens at the same time, and I am able to copy the serialport object, how does the connection behave? There can't be two open connections at the same time.