```ts
export function addOne(tally: Record<string, number>, name: string, amount: number): Record<string, number> {
  tally[name] = (tally[name] || 0) + amount;
  return tally;
}

export function mergeTally(left: Record<string, number>, right: Record<string, number>): Record<string, number> {
  const mergedTally: Record<string, number> = { ...left };
  Object.keys(right).forEach((key) => {
    if (mergedTally[key]) {
      mergedTally[key] += right[key];
    } else {
      mergedTally[key] = right[key];
    }
  });
  return mergedTally;
}
```