One column or two?

[winnipegleg]

I've got a Chinese Vevor 8 gallon system. I'm obviously new to this and I want to go from a closed system to an open one. Don't have enough cash for a 3" column but I have enough 1.5" copper pipe to make two 4 foot columns.
From what I've gathered, people think that a 1.5" column could take up to 12 hours to complete a 5 gallon mash. So I'm wondering if using two columns side by side as in the attached pic (not my best skill) would half that time or how long it might take and if it is practical to try this. Any ideas or help is more than welcome.