a = [{'name': 'zhangsan', 'score': 20}, {'name': 'lisi', 'score': 25}, {'name': 'zhangsan', 'score': 30}]
b = [{'name': item['name']} for item in a]
c = {item['name'] for item in a}
d = [{'name': item['name'], 'score': item['score'], 'freq': b.count({'name': item['name']})} for item in a]
e = []
for item in d:
if item['name'] in c:
e.append(item)
c.remove(item['name'])
print(e)

效果能实现，但感觉代码有点臃肿