Double diggle (likely a variant spelling or shorthand for "double diggler") is slang for the sexual act of simultaneously stroking or masturbating two penises at the same time—typically using both hands, one on each penis.
It's the same thing you described: jerking two penises together. The term comes up in adult contexts and porn as a specific type of double handjob, where one person pleasures two partners manually at once.
This sexual act is performed typically by a couple using a double ended dildo inserted into both anuses. From there, they proceed to bang each other, ass to ass.
Pajama casual is a term used when working from home and preparing for a video conference. All business above the waist and your pajama pants down below.