There are two issues with the code you provided.

First, the k value should be changed. You didn't share the part of your code where you defined k but it appears you are using k = 60. That should be changed to k = 2.

Second, you are initializing the rank at 1, when it should init at 0.

To make these changes take this code:

combined_scores = {}
k = ?????
for rank, point in enumerate(dense_results, start=1):
    if point.id not in combined_scores:
        combined_scores[point.id] = 0
    combined_scores[point.id] += 1 / (k + rank)

for rank, point in enumerate(sparse_results, start=1):
    if point.id not in combined_scores:
        combined_scores[point.id] = 0
    combined_scores[point.id] += 1 / (k + rank)

fused_results = sorted(combined_scores.items(), key=lambda x: x[1], reverse=True)

and change it to this:

combined_scores = {}
k = 2
for rank, point in enumerate(dense_results):
    if point.id not in combined_scores:
        combined_scores[point.id] = 0
    combined_scores[point.id] += 1 / (k + rank)

for rank, point in enumerate(sparse_results):
    if point.id not in combined_scores:
        combined_scores[point.id] = 0
    combined_scores[point.id] += 1 / (k + rank)