This is an ugly-ass Dick. Traveling back to Earth 2, it’s Dick’s Robin costume from when he grew too big for his short-pants and needed a better fit. He wore this (or rather, a version of this) just before he opted for the weird Batbin (Robman?) hybrid from yesterday. Then, when Earth 1 Dick came across Earth 2 Dick (in the stupid suit), Young Dick wore this as he worked with Old Dick.
One last Dick to bring this to a climax!