Hello, in Solidworks 2019. I could open two parts in two different instances. I like doing this because my files are not that big and I can use two screens. I upgraded to Solidworks 2020 and now it opens all of my parts in one instance. 

The trick to opening two instances was to go to "Open With..." select "2019 Solidworks"... Not "Solidwords Launcher". 

Right now, I have it to "Open With" Solidworks 2020 but it is not opening two instances. 

Please help, I really like using two screens to work with, sometimes three.