Do I need to insulate both hoses on a portable AC?
No.

You insulate the exhaust hot hose because you want exhaust air to stay hot until it is outside.  If heat radiates off the hose while still inside, that heats the house back up and partly negates the work your AC just did.

Usually you don't really care if your intake air gets a little cooler on the way in to the AC.  The only reason I can think of to insulate the intake hose is if your intake air (from outdoors) is also considerably hotter than your conditioned inside air, and you risk heating the inside just with your intake air.  I suppose if you are in a very hot climate and you are getting things really cool inside that might be the case.