дружка - bridesman
свашка (diminutive) - сваха - female marriage broker
плашка - billet, wooden block (to use as a base for axe chopping) - compare to плаха

The whole phrase looks like archaic-vernacular proverb. I can guess its meaning: "you(they) two are the same gang."

казеннокоштный - (vernacular) state-paid (funded by the state)