Wrong campaign tagged

When you say people have been tagged to the wrong Digital campaign do you mean, people qualified and run through another smart campaign than the intended one? The corrective action would depend on what flow you had in the incorrect campaign through which people flowed, e.g., if it was a Change Data Value flow step, you can always update the field's value to the previous value (you'd need to use Activities API to get Change Data Value activities if you don't have it in some sort of history field in Marketo that you could reference the value from), and then batch-run these people through the intended campaign.