double-bank

To row (a vessel) by rowers sitting side by side in twos on a bank or thwart.

To set two rowers to pulling (a single oar).

To ride (a horse, or bicycle) with two people on saddle

`We must double-bank my horse,' whispers Jim, `for a mile or two, till we're clear of the place; we didn't want to bring a lot of horses about.'

On this occasion we double-banked over on horseback without much difficulty; but very often the Hooker River is quite impassable with horses

To double up, to have two people doing something usually done just by one.

double-banked