Can I mix different cubensis strains in a PF cake?
Yes, you can. But most likely one strain will prevail, so inoculate each jar with its own strain.
Yes, you could. But there is not really a reason to. Most likely one strain will prevail, if you inoculate the jars each on 1 side you might get 2 strains fruiting from 1 cake. But in general it's better to inoculate each jar with its own strain.
Besides, when it comes to harvest time and you want to make your own spore prints, you wont know what they are. And no they wont be a new strain you created. Its a whole lot more complicated than just that.