Does copying a spell with a buyback cost also copy the buyback effect?

When you copy a spell, the copy is created on the stack with the same characteristics as the original — including its text, targets, and modes — but it was not cast, so no costs were paid for it (CR 706.10). Buyback is a keyword ability that functions during the casting of a spell: if you pay the additional buyback cost while casting, the spell's effect includes returning it to your hand (CR 702.27a).

Because the copy was never cast and no costs were paid for it, the buyback cost was never paid for the copy. The copy will resolve normally and then go to the graveyard, just like any spell without buyback would (CR 702.27b). The original spell, if its buyback cost was paid, will still return to the owner's hand when it resolves.

This means even if you copy a spell like Capsize where the original had buyback paid, the copy of Capsize will bounce its target but will end up in the graveyard rather than returning to anyone's hand.

For example: You cast Recoup targeting a sorcery in your graveyard, paying the buyback cost. An opponent copies your Recoup with Strionic Resonator. The copy resolves first, letting the opponent cast the targeted sorcery from your graveyard, and then the copy goes to the graveyard. Your original Recoup then resolves, and since you paid buyback, it returns to your hand.

The key rule is CR 706.10: copies are not cast, so no additional costs like buyback are ever paid for them. CR 702.27 confirms buyback only applies if the cost was paid during casting.